Great, Melany!  Here are updates and comments:

HELP ME - is it okay?  (Switch the order of the subject and the verb "to be" when you ask a question.  "Are you a lawyer?"  "Is it sunny today?" Use "OK" or "okay".)

Dear family,  (do you mean "friends"?)
I'm Melany and I'm 26 years old. I live in a small city of Sicily with my family and my pets animals. ("Of Sicily" isn't incorrect, but I would use "in Sicily".  "My animals" would often refer to farm animals, e.g., if you had a cow, a pig, some chickens, etc.  It's common to say "my pets" - a dog, a cat, a hamster, etc.)

I have a sunny personality. I really like cooking and walking.   (Perfect!)
I enjoy travelling and getting to know a new cultures. (Or "learning about new cultures") 
I would like to be an au pair to for learning a new language.  (Note "I would like to be..." in terms of a profession.)

Dear family, 

I'm Melany, 26, Italian girl, living in a town in Sicily with my family and pets ( animals if you live on a farm). I have a sunny personality and really like cooking and walking.
I enjoy travelling and getting to experience new cultures.
I would like to be an au pair , and improve my English/Spanish along the way

HELP ME is it OK?

Dear family,
I'm Melany and I'm a 26 years old. I live in a small city of Sicily with my family and my pets. I have a sunny personality and I really like cooking and walking.