We start with puppies by luring them. Holding a treat over their heads slowly move your hand backward, down the puppy's head and back, The puppy will follow the treat,  moving into a Sit position. Now, picture the movement. Eventually, it will evolve into your hand moving the treat by their head and up. Then it becomes simply holding your hand in front of you, bending the elbow , raising the hand quickly. So basically you will be moving your hand up, instead of down. Hope that was clear enough.