why buy something when you don't know how to use it? :think:
choose a sunny day, face 90 degrees to the sun, point to either the blue sky & clouds (not overcast!!) or foliage. With the CPL in hand, slowly slowly rotate the outer ring. Slowly because the saturation change is very slight to the naked eye, chances are that you'll miss it since you don't know what to look for. The saturation change comes and goes, so sooner or later (before the eyes tired) you'll notice some difference.
Better yet, shoot some pics with and without it. Follow the 90 degree rule for best effect.