Hi! I am learning english English. Can you correct it? Thanks.

Have you read the book that I gave you last month?
Is he writing his test? Yes He has been writing it since I arrived.
How many children do you have?
What work did you have after Tou had finished University? *
Have you ever seen the Northern Lights?
He lived in London for 3 years. He had studied there, before he understood that he don't **want to be a scientist.

* What was your job after you finished University? (Here in the US, we say "graduated college" or "finished school" as opposed to "finished University".)

** "didn't" woud be the correct usage here, at least in most places. In the American South, which is where I live, it is pretty common to hear someone say "He don't want that" or even more convoluted structures like "I ain't been wanting that", though. But it's not standard, so keep that in mind. I feel like more people you encounter will feel it is incorrect than will think it correct.

First notebook entry: Introducing myself

So (I think I see what is going on here, but this feels a bit awkward.), Hi everybody. I'm Esther. I live in Switzerland, in the German speaking part of it.I live in the German speaking part of Switzerland. I like to meet people and to ("to" can be omitted here.) talk to them. I easily get in contact with other people.It is easy for me to find people to talk to. I love this. But of course ("But of course" makes it sound like you are trying to assuage some fear that you might NOT like learning languages.) I also love languages. My two strongest ones are probably German and English followed by French and Italian. At the moment, I'm studying Espanol. My next entry, therefore, will be in Spanish. I'm hoping that I'll to get a lot of feedback.

Hi, everybody. I'm Esther. I live in the German speaking part of Switzerland. I like to meet and talk to people. It is easy for me to find people to talk to. I love this. I also love learning languages. My two strongest ones are probably German and English, followed by French and Italian. At the moment, I am studying Espanol. My next entry, therefore, will be in Spanish. I'm hoping to get a lot of feedback.

A Friend of Mine

Once ago, When I was in my third year on of secondary school, I got made a new friend. She was a girl with had such a tiny body figure small frame, and her face was pale, which shown obviously made it obvious that she was ill. It was my first time meeting her, but somehow most of my classmates already knew her because they had been in went to the same elementary school with as her.
I was told by one of my classmates that it had been a long time she didn't attend school and she was often absence during elementary school, when they were in elementary school, she was rarely in class. All of these were because This was due to the fact that she suffered from a serious nervous disease relating with nerve or sort of something like that. It was unexpected that she was would have been doing incredibly amazing well on in her study studies. She was one of the top scorers in English subject . Since that, I tried to approach her because I wanted to be friends with her. It's not that I was being snobbish toward her before, but I just didn't hadn't felt the need to pay attention to her. Well, maybe because I didn't really know how to handle an ill friend, and I had never got or meet met any of that kind of person before ever since in my life. So I just lived my life like I used to, but I never avoided her if she was asking for my favor. Other classmates seems to have a good term with her seemed to be on good terms with her, but they acted pretty like me. I knew we were being obnoxious and selfish towards her. One day, it happened to be The day before a festival was held in our school, I promised that I'll I would wait for her if I came to school early to school and then we would walked walk together during the festival. It's seems that I was the only hope for her to walk with as others seem busied seemed too busy to even cared about her. I couldn't say no to her when she asked me. On that time, I felt that I was stuck with her and I felt that it was hard to take the responsibility to look after her when all I got had in my head was just to enjoy myself on the fun moment of during the festival. I was rather be selfish on that time that day. that I left with my friends and broke our my promise to the girl. Now, I am stuck with this suck guilty feeling feeling guilty about my behavior towards her. She passed away two years ago, and I couldn't make it to ever got a chance to apologize to her anymore now I will never get a chance to apologize to her. My parents told me that all I can do now is just pray to Allah for her sake. Looking back to on the old immature side of me , I am sick of disgusted with myself. How could I be have been such a mean person, that I keep on ignoring her when she was there. I should had treated her as the way she deserved to be treated. After all, she was my friend. I'll keep her safe in my memory. May Allah bless her.

Good job! This story is really touching. We have similar stories, actually. There was this girl who was in my class growing up. Everyone made fun of her for being different and for not being "as pretty as" the other girls. Then, when we were in eighth grade, she was killed by a cancerous brain tumor. I can say that I was never guilty of being mean to her, but I never went out of my way to be a good friend, either. I still remember how I felt the day I heard the news. It's like they say, though. Nothing is worse than the indifference of good people when bad things happen. 

Uh. As far as your actual writing is concerned, you may want to review phrasal verbs, gerunds, and tense conjugations. Prepositions may need a bit of work, too. Remember to capitalize the first letter of all important words in a title. At your level, though, I'd say just keep reading material in English. You'll get the hang of things. But overall, this is a really good piece. You're doing fabulous!  :)

First notebook entry: Introducing myself

Hi, my name is Sebastian. I am from Medellin-Colombia.
I have I am 21 years old, and I study Sistems Systems Engineering (or "I am studying Systems Engineering"). 

When discussing age, English speakers tend to use the verb "to be" rather than the verb "to have". Moreover, "years old" can be omitted. For example: She is twenty years old. He is almost seventy years old (or "He is almost seventy"). I am eighteen years old (or "I am eighteen"). We are not five years old (or "We are not five"). Good luck with your English studies! It is an easy language to learn, but it is most certainly a difficult language to master. If you stick with it, I am sure you will do both! :)