Summarize this article:

Place your feet about shoulder width apart and plant them firmly on the ground. Bend your elbows and keep your elbows locked. Then, put up your fists so that they are guarding your face. Swing your right leg upward and aim for the area of your opponent's face just below the jaw. Be careful, this can cause the other person to lose consciousness.

Summary:
Stand in a solid stance. Protect your face. Lift your right leg up. Expect that your opponent will snap their head back and fall off-balance.