You haven't said what radio you have. I use an old Futaba 9-C and I'm sure it is a bit different then what you have. When we didn't have computer radios we set up throttle with the stick all the way down and that would kill the engine. The trim was also all the way down. When starting we would move the trim up about half way up and that opened the carb enough to start and idle, usually higher idle then needed. We set the trim to idle then flew the plane. When landed we just closed the trim switch. That would close the throttle and kill the engine. There were other ways to do it but that is pretty simple. I don't want to confuse you with how to set up the throttle at this point. I will tell you to get an instructor that can show you these little things hands on. It just makes life simpler and we all like simple.