Bringing home your first Pit Bull will prove to be an amazing experience as these guys are highly intelligent and make great family dogs. In fact, the origin of the breed was as a family dog, not as a fighting dog (these dogs are often trained to fight using very cruel methods). Keep in mind, you need to fully socialize your pup if you want them to be calm and friendly. This, along with the correct training methods will go a long way towards turning your new pup into a faithful family friend.
The task at hand is to teach your Pit Bull puppy that it is not okay for him to use your home as his personal bathroom and that in fact, he must go potty outside. Since Bullies are highly intelligent, the process often goes faster than with many other breeds. Keep in mind that during the training process your pup is going to have a few accidents, be sure to clean them up thoroughly using an enzymatic cleaner.
Before you start the training process, be sure you have plenty of time to work with your pup. During the early stages of the training process, you will be taking your pup outside as often as every 30 minutes. For those times when you can't be available to take him out on schedule, you should consider using a crate to keep him in a safe spot. The good news is that most pups won't go potty in their crate. You will only need a few other supplies to help you along the way, including treats and a leash.
Beyond this, you need to have plenty of patience as your pup learns what is expected of him. Be sure you work with your pup and, to a certain extent, let him set the pace. It might take a little longer this way, but the results will be well worth it.