So, sign up for SAT for June, and subject tests in October. Take practice tests online. Start researching schools. Prepare yourself for a lot of applications - and enormous competition from top students in India.
Read up on the US system in the links happymomof1 provided, and this thread:
http://talk.collegeconfidential.com/international-students/1698406-to-all-international-students-asking-for-huge-amounts-of-aid.html#latest
By the way, you should come up with a different major - aerospace internships and jobs will require a security clearance, for which you, as an international student, won’t be eligible. You should pick a field in which you can get a good job in India, because the reality is that most international students have to leave the country after they graduate.