MustangLife:
With the engine up to operating temperature, put your heater on full hot and put your gloves on. Next, squeeze the upper rad hose starting from the t-stat housing and working towards the rad. If there is air in there, it should burp out of the hose and into the tank. Doing this on an incline (like a driveway) is helpful but you need to chock your wheels and put the parking brake on!
HTH,
Chris