To do a heelflip you will stand in a position similar to the ollie but your back foot will go in the groove that connects the tail and the board. It will be on the side closest to you, opposite of the kickflip stance. Your front foot will be right behind the truck bolts, but your toes should hang over the edge of the board. Bend down and shift your weight to your back foot to pop the board, jump and take your back foot off while you drag your front foot off the board at the the groove of the nose and the board and flip the board, move your feet out of the way and let the board flip totaly then extend your legs back down to catch the board. Stomp down to land, make sure you are on the truck bolts. Keep your balance and roll away smoothly.