This is normal, you need more writing practice. I suggest that you use the italki Notebook at the top of the page to write something daily. There it will be corrected and commented on, so you will learn much quicker.

I read some things in English, and I can understand but when it comes to writing because I can not? --> If I can read in English, why is it so difficult to write in English? It's similar to learning how to play tennis. You can read a lot of books about how to play the game, but you actually have to pick up a tennis racket and hit a ball to truly understand it. It's the same with writing. You need to exercise your writing muscle. :)

i also like that before, but now i can write easily and even speak it up. i suggest that u must reading all the time u can. but it doesn't meant u must read anything u dont like b'cause it can make bored. so just read and write any story or maybe if u like comic u can read and excercise to write it. and trying to be more loved with english. because i think if u loved english u'll interest all about english and it'll very help u. siti

I keep reading, but only speak English on the Internet and for this very reason I end up using google. Thanks for your suggestion.

you just have to keep reading and try communicate with others in English, that will help you to write