I' m not Native speaker so my corrections can be not perfect) First try.

Hi, I want  to learn English very well.
I can understand English movies some parts.
My listening is not bad.
But I can't speak and I cant write very well.
Because my grammar knowledge is very bad.

If you want to learn Turkish I can help you.

I'm living in Istanbul. Istanbul is a very interesting city. Stupid, crazy and beautiful city. Everything is in the one city, it's interesting , isn't it?