Lots of good tools and info in that sticky .
 A quick way to determine the CG for a standard constant cord wing is to measure the cord from the leading edge to the trailing edge and then multiply that number by  33.3 percent. Then take the result and measure back from the leading edge and put a mark on the wing. This 1/3 measurement will be a good baseline to start with and 27 percent works well too for most planes.
If it's a low wing plane you need to invert the plane to balance it. If it's a high wing you balance it upright.
Once you get it balanced and flying, trim it out for normal flight then invert the plane and see how it behaves with "hands-off".. If it heads toward the deck it's nose heavy so  you can recalculate a lower CG percentage, remark the wing and re-balance it.