Hey, this is the first time that I write here. I'm a little confused about how to use this site, but with time I think I will understand how this works. I didin't didn't know how to start this text entry, and what should I to talk about, but so I decided to out here include a piece of a letter that I will use in my exchange to give to my future host family a chance to so they can know a little more about me. 

"I grew up in a condo with a lot of kids. On my vacation I spent most of the time at a beach house in Itanhaém, a small city in the coast of São Paulo state, with my cousins Ana and Raquel. My childhood was very funny and I had a lot of friends, but I was always were a calm kid.
I like to spend my free time at home, reading or watching TV series. I don’t like to go out a lot and I’m not a big fan of parties or staying out all night out. I prefer to stay at home enjoying my time with my mom and my pets. Talking about thats Speaking of pets... I must say that I absolutely love animals! I have 9 cats and 3 dogs. I know it’s a lot, but each one of them has a special place in my heart. if I could I would save all of the abandoned pets in the wolrd.
Last year I finished my college and I gradueted in advertising. I love this market and I already worked in two agencies of involved in event planning. I have a dream that one day I will have my own event planning agency."

Your English is clearly very good. However, I should say that you use too many commas. There were quite a lot of sentences that could have easily been split into two sentences.

About me

Hey, this is the first time that I am writing here. I'm a little confused about how to use this site, but with time I think I will understand how this it works. I didn't know how to start this text and what I should I talk about, but I decided to out paste here a piece of a letter that I will I'm going to use in my exchange to give to my future host family a chance to know more about me.

"I grew up in a condo with a lot of kids, on my during vacations I spent most of the time at a beach house in Itanhaém, which is a small city in on the coast in the state of São Paulo state, with my cousins Ana and Raquel. My childhood was very funny lots of fun and I had a lot of friends, but I always were was a calm kid.

I like to spend my free time at home, reading or watching tv series shows. I don’t like to go out a lot and I’m not a big fan of parties or staying out all night out. I prefer stay at home enjoying my time with my mom and my pets. Talking about that Speaking of (pets)... I absolutely love animals! I have 9 cats and 3 dogs, which I know, it’s a lot, but each one of them has a special place in my heart, if I could I would save all abandoned pets in the world.

Last year I finished my college, I graduated in advertising. I love this market industry and I have already worked in at two agencies of event planning agencies. I have a dream that one day I will have my own event planning agency."