First position your feet so that your back foot is on the tail and your front foot is in the middle of the board. Have your feet all the way on the board. Then when you are ready bend down, and then smack the tail as HARD as you can and then slide your front foot up, it should kind of be like a jumping motion. Try to stay with the board while ollieing.
Tip: If you can already ollie, here is a tip. When you are ollieing remember to try to time it perfecty; pop, drag ur foot and jump in a quick motion. This will give you more height.