Do not attemp this process if your engine is stil hot
I gallon coolant
The first step in the process is to open the raidator cap. This is done to ease the pressure in the radiator, though it may be minimal, and also provide a vent for air when the raidiator is being drained. Next loacte the drain plug normally found at the base of the radiator.
Once the cap is removed loacte the bung or plug normally found at the base of the radiator.
Once the plug is located go ahead and unscrew it until it is fully out. While it is being turned the coolant in the radiator will begin to leak from it so ensure that the container is in place to catch the leaking coolant.
Once all the coolant has been drained you can now go a head and replace the drain plug.
With the drain plug replaced you can now go ahead and pour in the fresh coolant. When the radiator is full remeber to top up the over flow bottle making sure not to over fill it but putting just enough as indicated by the lines on the bottle itself.
Once that is done proceed to start the engine and check for leaks.