i never heard of using a bell.
you can try taking the dog out on a daily routine/schedule. use treats and a catch phrase such as "big boy" at potty time. when he goes, say "big boy", immediately give the treat. after a couple days you can encourage him to go by saying "big boy" once in a while.
food is the great motivator, so it won't take your puppy long to associate going to the bathroom with getting his praise and a treat.
i would work to continue the schedule for up to six weeks. as the pup gets older, you will notice he won't have to go to the bathroom as often.