PCP is a dissociative drug, like ketamine or, MXE, or DXM. It is usually either sold as a powdered hydrochloride salt for insufflation/injection/plugging/oral use, or as a freebase either dissolved in solvents like ethyl ether, or "dipped" onto cigarettes, cannabis, or mint/parsely leaves.
It is very potent and long lasting. Dosage is 500ug to about 10mg depending on how fucked you wanna get. The half life of PCP is pretty long, an experience will generally last a few hours or more. If you have never done dissociatives before, I would be very, very careful with it. The dissociative experience is unlike any other, and for some people they can freak out and act erratically. (If you don't mind feeling numb and being unable to make any sense of your sensory input, you'll be fine...)
Assuming you have it on a cigarrete, one or two inhalations is all you should need to get effects. If you smoke too much you will find yourself unable to move and may just black out. PCP is an anesthetic after all.
The "horror stories" of people going totally insane and throwing cars around in traffic are mostly unfounded. Most people will just get unpleasantly disoriented and need to lay down. Just remember set and setting, go easy and don't redose if it's your first time, and don't smoke dippers around a police station or your anti-drug parents, and you'll be OK.