When teh car is cranking, teh relay (solenoid) on teh starter lets full votage go to the ignition coil. when you let off the cranking, a resistor reduces the voltage to the coil.

You are asking two questions here...how to hook up a starter (see answer above) but in teh post you mention alternator?

Which is it? I mean, they are not interchangeable in function, location or wiring hookup...