1997 Cadillac Seville STS Overheating

I have a 1997 Cadillac Seville STS with 164,000 miles on it. I recently had a radiator leak and removed the radiator and had it repaired. I also while everything was apart replaced the water pump and thermostat. I filled it with coolant let idle to check for any leaks. I drove it just a short distance and the temperature gauge went in the hot and a warning came across the dash that the engine was overheating and to stop. I got it home and the coolant was coming out of the overflow hose on the expansion tank. I talked to someone and they said that it is possible that it is airbound. How do I bled the air out? It never overheated on me before and all that I did was to remove the radiator and have it repaired.