Use a tape measure to find center of the cabinet door frame and mark with pencil. This creates a crosshair with horizontal line.
Line crosshair up with the hole in the jig, then mark the hole where you will pre-drill.
A jig has pre-measured holes that allow for exact placement of holes for cabinet hardware. Use small bit to make starter hole when drilling holes for pulls and knobs because you can't fix a hole that's too large for the screw. A smaller bit also prevents the hole on the backside of the cabinet from blowing out and splintering.