Look on the passenger side of the engine block, down under the exhaust manifold. There is a draincock there. You can slip a piece of rubber tubing over the tip to route it to your pan and wrench the nut to open it and drain nearly all the coolant out (make sure your heater control is on full heat.) There will probably still be a little coolant left in the lower hose and radiator when you're done.

Taking the radiator out/replacing it is really easy.