Stand on your board as you would for a regular ollie, but with your front foot hanging off slightly, towards the edge of your board(so only your front part of your foot is on the board).
Start your kickflip as if you were going to ollie but when your front foot reaches your nose, drag it off the side of the board, causing it to flip. Let your legs stay above your board, center your weight, catch it, and land on the trucks. Many people find learning the kickflip to be EXTREMELY frustrating, but you will get it sooner or later.
After mastering the kickflip, it's time to move on to the varial kickflip.