Use a food lure. Hold a treat in your hand, so your pup knows you have it. Hol dit by your left side where you want your pup's nose to be, say 'heel' and give the treat. Use another treat, walk a step or two, say 'heel' (if she is in the right place) and give the treat. Pup should stay in the correct position as she will follow the treat. Repeat, giving her a treat every few steps.