Here is a basic rundown of the ollie. As the site improves, the trick tips will become lots better--including pictures, videos, and more.
When you first attempt to learn how to ollie, you must have excellent balance on your board. Be comfortable riding down the street at high speeds. Ok, here we go!
1. Place your back foot on the tail of the board. Just about anywhere behind the bolts will do. You might find that the best pop will be acheived if you place your foot half on the tail and half hanging off. It just depends on the person.
2. Place you front foot about 2 inches behind the front bolts. So now, your back foot should be on the tail and your front foot about in the middle of your board.
3. Now, this is the really tricky part. The timing does it all right here. You must pop the tail of your board down with your back foot while jumping at the same time. As the nose of your board rises up as the tail pops the ground, slide your front foot up the board. Your shoe should be dragging along the griptape up towards the nose end of your board.
4. Slide your foot up until it hits the concave. The dragging motion should have pulled your board up higher and leveled it out. The dragging motion should have brought the tail end of the board to the same height as the nose. (Note: When you jump up and slide your foot up, try to suck your knees up to your chest. If you do the ollie just right, you should acheive maximum height.)
5. Get ready for the landing. Bend your knees when you land to absorb the shock. You don't want bad knees when you get old, do you?!
6. That's it! Hopefully you just ollied!
Don't get discouraged if you don't land the ollie first try! Try every day! Try hard! Don't give up! Also, your first ollies will only about an 1-2" high. Don't get discouraged! It's perfectly normal! Very few skaters started out by ollie 3 feet first try! As you practice more and more, your ollies will get higher and higher. Good luck!