I find it hard to beleive that the manual dosen't tell you where the CG is of that airplane. that's one of the most basic checks you make before you fly! Usually a trainer will balance at the main spar, usually right in front of where the wing LE sheeting ends. Or about 1/3 the chord of the wing. Search the forums and you'll find a LOT of advice about setting CG!

Balance that sucker and fly the wings off it!

Andy