Hello,

After completing 12th with science stream and if you age is above 17 years then you will be eligible to apply for CPL training.
Once you will clear the training program from an Institute recognized by the Civil Aviation Authority of that particular country then you can become a commercial pilot.DGCA provides CPL training in India and issues the license after training.

For applying for CPL you need to go through Pilot Aptitude Test.The test consists of 3 stages which are written examination, Interview and the Aptitude Test.After clearing the test you will be selected.

I hope this helps.