can someone tell me how do you flush the radiator

 

It's not just the radiator you want to flush by the entire system. I bought a cheap kit where you have to cut into the heather hose and hook a garden hose into an adapter, then you run the water and flush through the system with the heater running as far as I remember. My advice though is to replace that heater hose after because I believe you could just leave the fitting in there. I figure changing a hose once in a while is no big deal.