I had to do what Steve is saying to start learning rudder. I had one of the better instructors for my basic flight training plus I started with A 2 ch plane, rudder and elevator only. As soon as I went to A plane with ailerons and throttle I was no longer using the rudder?? I kept asking about it and got A number of different answers from him and different club members.
A couple of years later I discovered my basic instructor really didn't understand it either.
As luck would have it my advanced instructor was an IMAC pilot, then I learned how to use it and when.
Some of my big scale planes, bipes for the most part needed rudder input just to turn correctly for scale flight.
Today I don't think I could land without my rudder, well, I can but it's second nature for me to land using rudder, elevator and throttle only, I just keep the pane level with the ailerons.
Take your plane up and play with the rudder then seek out A good pattern pilot to help you understand it better.
Nathan said it right, too hard to teach from long distance and on A computer.