Cappaj1,
Ok, old non-computer radios first. On these radios you set the engine throttle so that it is completely closed when the stick is fully down and the trim tab is all the way down as well. Then when you fly you move the trim tab up to where the engine idles. While it may sound like you are chasing the idle it's really not that bad. I move the trim tab all the way up and then when the engine starts I come back down to where it idles. When I'm done flying I simply use the trim tab to it's lowest setting which will kill the engine.

For computer radios with digital trims. Most of these will have either a throttle cut button/switch preprogrammed, or give you the ability to set up a throttle cut. These you simply activate the throttle cut which will close the barrel of the carb and kill the engine.

Hope this helps

Ken