Go to the bathroom and start to urinate, then stop the flow of urine. The muscles you just used to stop the flow of urine is your pc muscles.
Do not focus on the buttocks, abdominal or stomach muscle.
This works for both men and women.
Practice stopping the urination mid-flow; the more you practice, the better you'll have an idea of where the kegel muscle is and what it feels like stimulating the kegel muscles to contract it.
(Women) can insert one or two fingers in the vagina, and try to squeeze your fingers. The muscle you're using to squeeze your fingers is your kegel muscles; focus on what it feels like to flex it and then practice without inserting your fingers.
It might help to pretend that you're stopping the flow of urine, even though you're not actually urinating.
(Men) should try to make their erect penis jump or twitch. The Kegel muscle shifts the erect penis once you've locating the pelvic floor muscles and practiced flexing it, using the movement of your erect penis as visual feedback, you can then practice flexing it.