if your dog stays put, reward it with a treat.
if you notice that your dog has moved or is trying to move during the time you have asked it to stay, raise one of your hands right above its head. you can do this with its leash as well. let it stay there for a little while before bringing it down and then put your hand back to its original position.
you do not have to repeat your command right now. count to 30 and go back to your dog. you are to keep your body completely straight during this process and make sure you are not leaning over your dog. 