My English is very weak. How to improve it?

Hi Deep, first of all, you have to learn the basic foundation of the English language. Then learn Grammar, and the rest of the topics will follow.
Listening to English news(Indian channel) will help you with the sounds and Vocabulary. Secondly, read small stories and try to know the meaning of words. Attend English speaking courses nearby.

You can improve your English only through continuous practice and patience while learning.
You can improve your English by focussing on improving your Reading, Listening, Speaking and Writing Skills.
I recommend you learn English from online resources or through one to one coaching by an educator on UrbanPro.

First of all, try to learn about tenses. Then start reading novels and daily newspapers. The newspapers will be a bit challenging at first, but you will begin learning new words and buy a good dictionary for word meaning. Then start reading some literature books of class 10th and 9th that will provide you with a bit of knowledge about the old style of English. And try to speak English in front of the mirror so that you get a perception of how your English speech is and improve it.
Then you will start to understand fluent English like movies, t.v. Shows and always get subtitles so that you can understand the correct pronunciation of words in different accents.
 It will improve your English very fast and try to talk to someone in English at your home. That will give you confidence in speaking it more often.
 Good luck!

Hi!
Here are some of the simple steps you can follow. As you wake up early in the morning, do start reading one page of self-help books that will make your day productive. Read English newspaper, listen to English songs, enjoy english documentaries and movies. You can do self-introspection by standing in front of a mirror and communicating with yourself. It will surely boost your self-esteem.
See you at the top.
Good luck!