Put a Y- on the throttle and the battery, thus using 1 channel
(note: you can plug the Y ( not a reversing Y )into any channel and accomplish the same with the battery lead. I simply suggested the throttle servo), 2 ch. for ailerons, 2 ch. for flaps, 1 ch for elevators, 1 for rudder. The 7 channel Rx. you have will be fine with this set up. Again, I used the 8 channel Rx. simply because I had one and therefore didn't need to use the Y. Either way is fine.

You will need to read up on your Tx. and the Ultrastick book that came with the kit so you better understand how to set up the airplane and do the mixing and switch selections. This can be confusing and difficult to try and explain in RCU threads. Use the book to take you through each step. I promise it will be easier this way.