I would recommend adjusting the trims mechanically (on the plane) so you can get the trims set to neutral on the radio. It's just easier.

As for the radio, I have the same one. Turn it on. Push both of the programming switches up and you'll enter programming mode for the current model (it has two-model memory as I recall). Push the left programming button up to select what you're working with (sub-trim, rev-norm, end-point adjusment, etc.) and push it down to select the control to modify (ELE, AIL, GER, RUD, etc.). Use the right programming switch to shift the values for these items up or down.

EDIT: To enter the main programming mode (to set model name, reset model, etc.) have the TX off, hold both programming buttons up and turn it on. Then it enters the main programming mode. You can name your two models, set flaperons or v-tail or whatever, reset the model (clear all entries), and one or two other things I can't remember right now.