How do I bleed the coolant system, it is over heating at the gage and acting spuradic on 1995 Ford Ranger

It seems as though there is air in the system, the shop put a new radiator in and this problem is occuring, cant take it back because it was 6 months ago when they replaced it. Since then I have replaced the thermostat, and the problem still exist. They did change the heater control valve as well when they did the radiator replacement. And yes it does not heat up for a long while even when the gage saids hot the heater blows cold air. After running for maybe 5 miles it will get warm. Now should my fan run all the time or should it turn of sometimes? It constantly runs.

Asked by for the 1995 Ford Ranger
Bleeding the cooling system: get the engine hot, burp the coolant cap (CAREFULLY - you can burn yourself without protection!), allow air and some coolant to boil over, Refill coolant level...

Repeat the procedure until no further air burps out.