1994 Ford Aerostar radiator

What do you mean, "still"? Is that why you replaced the radiator? Have you looked into a leaking cylinder head gasket? That can allow combustion gases to get into the cooling system where it can pool under the thermostat. Thermostats won't open in hot air. They have to be hit with hot liquid. The clue is the upper radiator hose will be cool and thumping.

I really need to know how to get the air out of the lines and where the bleeder valve for the radiator is.

Follow the upper radiator hose to the thermostat housing on the engine. If there is a bleeder screw, it will be on that housing. If there is none, look for a threaded plug or a sensor you can unscrew. If you have to take a sensor out, leave the ignition switch off when you unplug it to avoid setting a false diagnostic fault code.