After they sleep, eat, or play hard, they have to go out. At first they will sleep a lot, so watch for them to wake up, because once they wake up, they need to go potty. It won't be long before they will be ringing the bells when then need to go potty. Once they learn that ringing the bells will get them outside, they will try that game with you. You just can't put them outside, you have to be with them to keep their mind on why they're out.
Puppies have a short attention span and a large amount of curiosity.
If you want your dog to be an inside dog, you need to go through this process. The bells make it nice for when they're ready to go out and you're in another room unable to see them watching the door, you can hear the bells and know that it's time.