In order to be eligible to become a pilot after your 12th class you must have Mathematics and Physics as subjects in 10+2. 

You need a medical certificate as well for which you can join  various aviation schools. 

Then you have to do course and get the requisite training as well as flying hours of 250 hours then you can apply for the commercial pilot license

After getting a license you can join a training of cadet pilot programme.

You can check the top flying institutes below

Indira Gandhi Rashtriya Uran Akademi (IGRUA)

National Flying Training Institute (NFTI)

Madhya Pradesh Flying Club (MPFC)

Ahmedabad Aviation & Aeronautics Ltd. (AAA)

Bombay Flying Club

Good luck!!