I don't know your car but assume it's a V8. There should be a drain plug on each side. If I recall right, Larry Bible has described a flushing routine, but it might have been a different car. Do a search and you will get an idea.
If you do it with the car running, you would want the heater or defrost on, so the water will circulate through the heater element.
I did a flush with citric acid and had the stuff circulating through the engine for 15 minutes with heater on.
Somebody else can probably provide more details for your specific car.