how can i improve my English ?

Well, isn't that a broad question :D The ways of improving your English are extremely numerous. I would recommend starting by determining your best way of learning anything else: If you have good listening memory or can easily imitate speech, you can try watching movies without dubbing or subtitles and remembering the sound of English. Maybe you are an analytical, visual learner - then I would recommend reading books and writing down each word. The classic way of language books is often looked down on, but it is a time-proven technique. And, of course, tutoring! :D