To do a ollie, first put your back foot on the tail and your front foot just behind the front truck bolts. Then bend your knees and shift your weight to the back foot and push down on it to pop it on the ground. After you do that jump and slide your front foot up the board, while lifting the back foot in the air. Lifting your back foot will level you out in the air. Once your level get ready to land by extending your legs back down. When you touch the ground bend your knees with the weight of your body to spread out the impact. The ollie is the most basic skate trick once you learn it you are ready for more advanced tricks.
Tip: When landing make sure your feet are on the truck bolts, or you might crack or split your deck.