Yea i know how you use it. all my dogs ring bells to go outside. (you might need a clicker trainre for this though that is how i did it.)
You put the bell as low as the puppy. Now everytime you are about to take him out walk him past the bell so his body touches it. As soon as it makes a noise open up the door and let him outside. At first he wont notice but after a couple of days doing this he will catch on. Also everytime you open up that door the bell will ring so the dog will associate that door opening with that bell ringing.
Now when the dog catches on he might go and start "playing" with the bell if he rings it make him go outside even if for a second so that way he realizes "Oh if I ring it I have to go outside"
Hope that helps you out!!!