Stand with your feet shoulder-width apart.
Bend your legs slightly, then take either foot and tap it on the floor next to the inside of your other foot while straightening your knees.
Bend your legs again, put the tapping foot back where it came from and straighten your knees again. Reverse.
Do this while turning your body slightly in different directions, once you can do this in repeatedly in quick succession.
Practice the moves slowly until you feel completely comfortable doing them. Increase your speed gradually. Arms should remain bent and at your sides.
When you have the rhythm, start placing the tapping foot forward or back of the stationary foot for more variety in your dance. Or you may skip the tap all together if doing so doesn't cause you to miss the beat.