How can I clear CAT : I am from a tier 3 state. And only started English from 8th standard.

Hello,

Nothing is impossible! You can start with practicing your grammar, also solving language section of mock tests available online and practice essay writing to time yourself as well as assess your comprehension skills.

Start reading newspapers (specially the editorial section) and story books.

Also, here are ten websites you can visit to improve your English!

You can also have a look at ways to speak fluent English!

And by the way...your question is grammatically correct! ;)