You have three adjustments on your shock: Spring preload, compression damping and rebound damping. The compression damping is the black knob on the shock resivour and the rebound damping is a knurled ring (probably also black?) on the bottom of the shock, down by the lower shock mount.
The damping, wether compression or rebound, is an adjustment of the speed in which the shock compresses or rebounds. The adjustmets generally only adjusts the "low speed" regoin of shock action. The spring sag, if the spring is correct for your weight, is set to sag numbers and left alone, for the most part.
Damping adjustmets are made buy counting clicks or turns from full hard, which is to say fully closed. Lefty-loosey, righty-tighty still applies here. So if someone says they have their compression set at 10 turns or the rebound is 8 clicks, they are talking from fully seated.
Have fun and post up what you find.