This exercise of walking your dog can be done without a leash in an enclosed safe area or on a long line. Luring teaches your puppy to focus on you and sit when you stop.
If the puppy is jumping up, then you are holding the treat too high. For a tiny pup such as a toy breed, you will need to bend down to make sure your pup is staying focused on the treat. Or, use a wooden spoon with a sticky treat, such as peanut butter, to avoid having to bend over.
Once the pup is walking for a short distance and you are feeling comfortable with what you need to do, you can start to cover more ground, change directions, and change your pace. Remember to break often (release the puppy) from the luring and enjoy a quick game. (see Games).
Gradually start to fade the lure so the puppy is following you not the food. Continue to stop every 3-4 steps and give the pup a treat.