Your puppy will be standing on his tail, maybe even moving a few steps - just like a human would do!
How to do it
Starting from the 'Sit' position, hold a treat right in front of the nose of your dog, then say 'Stand!' and move it above him so that he will have to stand in order to reach it. As soon as he stands say 'Good boy' and, when he sits back, give him the treat. While he is standing you can move - just a few steps - holding the treat - cheer him a lot if he follows you "walking".
Tips & Tricks
When you hold the treat above your dog and when he is standing move your fingers: this way he will recognize that movement as the visual signal 'Stand'. Otherwise he will stand every time you hold something above him - and this is not always nice...