The diving header technique gives a football player that extra edge and versatility to get to the ball first, and to get a head on crosses that otherwise would be missed. This is particularly true at the near post where the attacker is trying to get in front of the defender. It's a great soccer skill to perfect, and one of the best coaching drills is illustrated in the photograph.
The diving header require getting both feet off the ground, and a jump towards the football. You should be almost horizontal as you head the ball, using your forehead as always. Generally, take off is from only one foot, because the diving header is usually attempted on the run.
Most players find the dive the most difficult part of this technique. If you are having problems, practise the dive first without the ball. Put a low hurdle down, such as a large bag, a couple of twigs, or even a player crouched down if you can find a volunteer! Jump over the hurdle without hesitating. Then try the same thing with a partner serving the ball, so that you have to jump over the hurdle to head the ball.
Jumping over an obstacle is a great method of learning the diving header as it forces both feet to leave the ground.