To find it, look for a small, usually plastic valve with a hose connected to it. One hose will go to the intake manifold, and the other will be connected to the valve cover itself. It's often a dark-colored plastic piece.
Because there's some minor variation depending on engine type and even minor model differences within the 1996 Blazer lineup, it's best to consult a repair manual specific to your Blazer's engine for a precise diagram. A quick online search for "1996 Chevrolet Blazer [your engine size] PCV valve location" with images should also help you pinpoint it visually.