i battery kept going dead then i bought a altrnor and the car still will not start

I would double check the battery connections. They must be clean and tight. Also inspect the battery cable ends. If they are old they might not be tightening all the way up or be cracked not allowing a perfect connection. Also clean and tighten the negative battery connections on the frame and motor

First check the battery connections, then make sure the alternator wires are on correctly and tightened. Was the alternator wire connectors painted? If so remove the paint with a small copper wire brush. Once started, does the dash ammeter show you are charging? I'm not to clear on your question about the light coming on. Check the battery also, does it need charging? If you started with a dead battery, you can change everything but if no charge, nothing will work. If you can jump start the car, it is not the starter. You must have a charged battery, once it is running, the alternator must work and charge the battery. If the battery is receiving a charge, is the wiring properly grounded and clean to receive a full charge. If the car starts with a jump charge, is the battery good or need to be replaced. It will acdept a charge, but if a bad cell is in there, it will not hold a charge.