Depends on the rad but on some designs there is a big plastic screw on the bottom rear left, failing that just pull a hose. There is no bleed valves as all the air in the system should find its way to the header tank.
When I changed the engine in my 1.4 there was a plastic plug at the bottom of the radiator. As for bleed you just leave the expansion tank cap out and get the engine running for some minutes and it will bleed itself.