My favourite books

I really like reading. In my opinion, it's a really good way to forget about your problems and real life for some hours. It may not sounds good, but sometimes, if I'm sad, I need to think about someone else's problems to feel better. But I'm not such a bad person! So I prefer reading so that , the problems are not real :) (Just like lynn said, what you are trying to say is not clear from this sentence. So maybe something like what lynn said or something like "I prefer reading where I am in an imaginary world where my problems do not seem real")

I love thriller books. I think that this kind of books makes you continue reading until it ends. You can't stop! (A better phrase would be "... book keeps you engrossed right till the end")

Some of the books I'd recommend would be the following ones:
Firstly, I must write about my favourite writer. He's Spanish and he's (Using 'he is' twice can be avoided) called Carlos Ruiz Zafón. I think he's quite famous not only in Spain but also in other countries. His best book is The shadow of the wind. The story that he tells is very interesting and the book is even better because he writes about Barcelona, so I know what he's writting  writing about. It He/ The book/ His writing makes you feel that you're part of the story. (Since the last sentence is about his writing and about the story, there is lack of context in the next sentence. So you must use the complete subject rather than just 'It')

On the other hand, I also love Swedish thrillers. When I say thatSwedish thrillers (that is unclear because it may mean "swedish thrillers" or your statement that you love them), everybody thinks about Stieg Larsson and (his famous work -) Millennium, but I read the first book and I didn't really like it as it's too long and he sometimes writes about topics (that) I don't understand (for example, economics).(Stieg Larsson is a human and Millenium is a book. Since you are introducing these two words for the first time in the writing, it is better to put a clarifier stating that Millenium is actually Larsson's book. there is no need for 'first' as what 'first' signifies is not clear here.)  For this reason, my favourite Swedish writer is Camilla Läckberg. I've already read six of her books and I'm waiting for two others, as they're not able in Spanish yet. All of her books are based on a little town in Sweden where some murders take place and police try to find who the murderer is. (Same corrections as lynn)

As you can see, I love reading. In fact, I'd like to read more, but because of (the time taken by my studies at) the university, I don't have enough time to read all the books (that) I want to (read).

You are very good at English. I have tried to point out the minutest of mistakes according to my knowledge. In fact, your writing can be passed off as without any major mistakes because most of the mistakes here are OK in general use. I wish someday, i'd be as good in spanish as you are in english :)

My favourite books

I really like reading. In my opinion, it's a really good way to forget about your problems and real life for some hours. It may not sounds good, but sometimes, if I'm sad, I need to think about someone else's problems to feel better. But I'm not such a bad person! So I prefer reading so that the problems are not real :)

I love thriller books. I think that this kind of books makes you continue reading until it ends. You can't stop! ("this" needs a singular noun. A phrase like "keeps you reading until the last page" would be more conversational, but your version is otherwise fine)
Some of the books I'd recommend would be the following ones:
Firstly, I must write about my favourite writer. He's Spanish and he's called Carlos Ruiz Zafón. I think he's quite famous not only in Spain but also in other countries. His best book is The Shadow of the Wind. The story that he tells is very interesting and the book is even better because he writes about Barcelona, so I know what he's writting about. It makes you feel that you're part of the story.
On the other hand, I also love Swedish thrillers. When I say that, everybody thinks about Stieg Larsson and Millennium, but I read the first book and I didn't really like it as it's too long and he sometimes writes about topics I don't understand (for example, economics). For this reason, my favourite Swedish writer is Camilla Läckberg. I've already read six of her books and I'm waiting for two others, as they're not able in Spanish yet. All of her books are based on a little town in Sweden where some murders take place and police try to find who the murderer is.

As you can see, I love reading. In fact, I'd like to read more, but because of university I don't have enough time to read all the books I want to read.

My favourite books

I really like reading. In my opinion, it's a really good way to forget about your problems and real life for some hours. It may not sound good, but sometimes, if I'm sad, I need to think about someone else's problems to feel better. But I'm not such a bad person! So I prefer to be indulged in reading, as if the problems were not real.:)

I love thriller books. I think that this kind of books keeps you continue reading till the end. You can't stop!
Some of the books I'd recommend would be the following ones:
Firstly, I must write about my favourite writer. He's Spanish and he's called Carlos Ruiz Zafón. I think he's quite famous not only in Spain but also in other countries. His masterpiece is The shadow of the wind. The story that he tells is very interesting and the book is even better because he writes about Barcelona, so I know what he's writting about. It makes you feel that you're part of the story.
On the other hand, I also love Swedish thrillers. When I say that, everybody thinks about Stieg Larsson and Millennium, but I read the first book and I didn't really like it as it's too long and he sometimes writes about topics I don't understand (for example, economics). For this reason, my favourite Swedish writer is Camilla Läckberg. I've already read six of her books and I'm waiting for two others, as they're not available in Spanish yet. All of her books are based on a little town in Sweden where some murders take place and police try to find out who the murderer is.

As you can see, I love reading. In fact, I'd like to read more, but because of university I don't have enough time to read all the books I want to read.

My favourite books

I really like reading. In my opinion, it's a really good way to forget about your problems and real life for some(a few) hours. It may not sounds good, but sometimes, if I'm sad, I need to think about someone else's problems to feel better. But I'm not such a bad person! So I prefer reading so that the problems are not real :) --> This sentence does not contain a touchable meaning.

I love thriller books. I think that this kind of books makes you continue reading it until it the end. You can't stop!
Some of the books I'd recommend would be the following ones:
Firstly(first of all), I must write about my favourite writer. He's Spanish and he's called Carlos Ruiz Zafón. I think he's quite famous not only in Spain but also in other countries. His best book is The shadow of the wind. The story that he tells is very interesting and the book is even better because he writes about Barcelona, so I know what he's writting about. It makes you feel that you're part of the story.
On the other hand, I also love Swedish thrillers. When I say that(when I talk about it), everybody thinks about Stieg Larsson and Millennium, but I read the first book and I didn't really like it as it's too long and he sometimes he writes about the topics which I don't understand (for example, economics). For this reason, my favourite Swedish writer is Camilla Läckberg. I've already read six of her books and I'm waiting for two others, as they're not able in Spanish yet. All of her books are based on a little town in Sweden where some murders take place and the police try to find who the murderer is.

As you can see, I love reading. In fact, I'd like to read more, but because of university I don't have enough time to read all the books I want to read.

You write very well, well done my friends, but, there are also some other mistakes that I couldn't correct.

Good luck. :)

My favourite books

I really like reading. In my opinion, it's a really good way to forget about your problems and real life for some hours. It may not sounds good, but sometimes, if I'm sad, I need to think about someone else's problems to feel better. But I'm not such a bad person! So I prefer reading so that the problems are not real :) (I don't really know what you want to say here, maybe "I prefer reading so that my problems don't seem that real")

I love thriller books. I think that this kind/these kinds of books make(s) you continue/go on reading until it ends. You can't stop!
Some of the books I'd recommend would be the following (ones):
Firstly, I must/would like to write about my favourite writer/author. He's Spanish and he's called Carlos Ruiz Zafón. I think he's quite famous not only in Spain but also in other countries. His best book is The shadow of the wind. The story that he tells is very interesting and the book is even better because he writes about Barcelona, so I know what he's writting about. It makes you feel that you're part of the story.
On the other hand, I also love Swedish thrillers. When I say that, everybody thinks about Stieg Larsson and Millennium, but I read the first book and I didn't really like it as it's too long and he sometimes writes about topics I don't understand (for example, economics). For this reason, my favourite Swedish writer is Camilla Läckberg. I've already read six of her books and I'm waiting for two others/further, as they're not yet able available in Spanish yet. All of her books are based on set in a little town in Sweden where some murders take place and the police tryies to find who the murderer is. (find the murderer OR find out who the murderer is)

As you can see, I love reading. In fact, I'd like to read more, but because of university I don't have enough time to read all the books I want to read.

You really are very good already, keep on writing and maybe reading in English :)