The rudder and ailerons don't exactly get used together. The amounts of the mix vary during the turn. You generally initiate the turn by using the ailerons to bank the plane. Once the desired bank angle is established, the rudder and elevator are used together to make the plane track through the turn and the ailerons should be neutral during the turn. To end the turn, the rudder and elevator return to neutral and opposite aileron is used to return the wings to level.
On a trainer, if you have to hold aileron to keep the plane in a bank during a turn, you aren't using enough rudder.

This is another reason to learn to use the rudder rather than relying on aileron to rudder mixing, although even that is better than not using the rudder at all.