Persistence is the key. You hang the bells on whatever door you intend to let the puppy out of to go potty and while the puppy is still small you just take her to the door and use either her nose or paw to "tap" the bells. As you ring the bells tell her "potty" or "outside", but ALWAYS use one word and the same word every time. If she potties outside praise her with enthusiasm and bring her back inside.
I do not make or sell Poochie Bells, so I suggest if you are interested in this method to go on Amazon.com