Ahh, well that link helps quite a bit! The Center of Gravity should be right at the wing spar that runs along the front third of the wing and is visible underneath the covering. If you can balance the plane at that spar, it should fly just fine.

As for servo and battery placement, that too is a function of getting the CG to come out at the wing spar. You will be limited in your ability to move the servos, the glider came with control rods of a certain length, so you'll need to mount the servos where ever they work best from a control standpoint. With that done, you simply need to move the battery and receiver around inside the fuselage as best you can until the glider balances on the wing spar.

Good luck, and if you need more specific information, you will probably need to call Hobby-Lobby for customer support.