John's right. Don't worry about doing it yourself -- just go to a reputable pro shop and have them measure your PAP for you.
To give you an idea of what's going on, without going into huge details..
PAP is short for Positive Axis Point. This is the spot on the ball that is used as a reference when drilling the ball. Everybody's PAP location is different, since it's determined by how you throw the ball. The PAP is on the exact opposite side of the ball from the center of your ball's track as it rolls down the lane. As the ball comes off your hand, it's rotating along an imaginary line that goes through the center of your track and the PAP.
All this tells you and your ball driller is how to place the pin, CG, and mass bias when drilling the ball to get the reaction you want. As an example: If your PAP is 4" straight across from the center of your grip, but your teammate's PAP is 5.5" straight across from the center of his grip, this means that if the two of you could throw the same bowling ball with the pin at grip center, you'd get different results. The pin placement will be a full 1.5" closer to your axis point, which means the ball will flare more than your teammate whose axis point is further away from the pin. Your ball driller should understand what this means when choosing how to drill a ball for you (early hook, late hook, angular, rolly, etc.)
