Hello Elgharbi ,
To improve your english there are several methods to apply ,from which you choose the most suitable for you ,those methods that make you learn quicker and more efficient .
Some of those methods are :
-Read at your own level of understanding ,you can read simple books ,magazines , articles online or
offline to increase your vocabulary and look up new words instantly in a dictionary to update always
your vocabulary .
-Listen to English lyrics of songs , watch movies in English , all that will increase your vocabulary and
your modes of expression .
- Speak with native English speakers and practice with them ,it will allow you to pick the native accent
and many native expressions .If you don't have the chance to speak with natives in your surrounding
you can use online chatting programs to practice voice chat with natives ,it is a very effective tool
to improve communication skills ,speaking and listening etc.
-Do any activities that involve using the English language and that you enjoy doing such as games , for
example Scrabble is a game where you compete in building words using crossword-like board ,it is a game yet a good way to increase your vocabulary while having fun .
- Do exercise grammar in order to build correct sentences ,you can use grammar books or online
grammar exercises .
Combining all the above mentioned methods or some of them will lead to a gradual improvement .
How long it would take to reach a certain level of fluency in English will depend on how much
effort and time you will dedicate for learning .So good luck and hope those tips would help:)