Tricks » Kickflip
We wouldn't call this website KickFlip.co.nz without teaching you how to do them!
The general stance is to have your back foot on the tail, just like an ollie, but your front foot would be slightly off the back off the side of the board more (about half way off the board). Some people also like to angle their foot, pointing to the nose of the board a bit.
This video explains it well:
Once you can do a stand-still kickflip, try doing them moving, then doing them over / off stuff.