flushing radiator

I have a 1999 Deville. I have read several posts on Dex Cool vs The Green Stuff. I guess I will stick to Dex cool unless someone gives me good advice otherwise.  My main question is what do you mean when you say reverse flush?  What are the steps for this?

Reverse flushing is when you run water thur cooling system in the oposite direction as designed. The idea is to loosen trash in system and wash it out. Thermostat normally has to be removed to do it.