The easiest part for a homeowner is to condition the bedknife. The cutting cylinder(blades) pushes the grass against a piece of metal (bedknife)on the bottom of the mower. The front of the bedknife becomes rounded over with use. You want a nice right angle corner on the bedknife where the cylinder pushes the grass against it. You can use a metal file or a finishing grinder.
Backlapping is used in order to have uniform clearance between the cylinder and the bedknife. First you find the adjustment mechanism and adjust the clearnace. Then you find a way to spin the reel BACKWARDS. You apply a grinding compound and slowly tighten the clearance til it is uniform.