The heelflip is another street staple and works on a very similar principle to the kickflip. The main difference, as you might have guessed, is that with the heelflip it's the heel that does the flipping, not the toe, and that the board rotates in an anti-clockwise direction, unlike the kickflip.
For a Heelflip, it's pretty much the same thing as a Kickflip, but you're using your heel to flick it.
You put your back foot on where you do an ollie or a kick flip. You put your front foot more in the middle of your board.
Leave your toe's hanging off the edge a bit so you can flick it off with your heel.
When you've done your ollie motion, snatch your back tail, flick your heel off, wait for it to do a full rotation.
Wait for the grip to put your feet down on the bolts, and land it on the floor, roll way.