the Center of Gravity! is by far the most important thing of all! I have no experience with that plane, but it has wings, so I might be able too give a lil insight!

I also am not an DX7 user, but I will assume that you can set-up your transmitter, the controls or not much different then a heli, as long as you get your trans. into airplane mode!
the control throws should be in your instructions,

mode 2 planes, have the elevator and ailerons on the right stick.
throttle and rudder on the left stick!

when you pull back on right stick, the elevator should go up! and vice versa!
when you push the right stick too the right, the right aileron should go up, and left on should go down!
rudder (left stick) when pushed too the left, the rear of the rudder should go in the same direction as the stick, when looking at the plane from the rear!
in fact all references refer too the plane from the rear!

don't know if that is what you are looking for, but thought I would try! good luck, if you can fly a heli, you should have no prob. with that plane!