It isn't really clear from your post whether you have (or had) a CA, and the procedures are different if you are certified in another country, move here, and establish certification in the US. I'm assuming that you don't have a CA, because it sounds like you didn't take all the exams. Therefore, in this country, you have start the process over. I am not sure whether your college degree in India is acceptable here to qualify you to take the CPA exam. You will need to contact NASBA and/or the state board of accountancy to determine that. If the college education you received in India is acceptable, you will need to register and pay to take the exam here. If it isn't, you will need to find out from the state board/NASBA what education is necessary to remedy the deficiency.
Assuming that you are employed in Pennsylvania in public accounting and that your education in India is sufficient to qualify you to sit the exam, you are eligible to sit the exam in Pennsylvania. Licensure requirements in Pennsylvania are found at www.dos.state.pa.gov/bpoa/, follow to business boards, then to accounting. The NASBA website has information about the CPA exam and links to all the state boards. You also should know that Pennsylvania has an experience requirement which includes a significant amount of attest experience, not only tax experience. You'll need to verify with your employer that your experience is being supervised by a current licensee and that it will be eligible for qualifying experience once you pass the exam. Good luck!