Prong collars (also called 'pinch collars') are a series of chain links with blunted open ends turned towards the dog's neck. The design of the prong collar is such that it has a limited circumference unlike slip collars which do not have a limit on how far they can constrict on a dog's neck. The limited traction of the martingale chain combined with the angle of the prongs prevents the prongs moving close enough to pinch. The collar is designed to prevent the dog from pulling by applying pressure at each point against the dog's neck.
Unless you plan to keep your dog outdoors--and few of us do because it's not recommended--you'll need to teach your dog where to eliminate. Therefore, house training (also called housebreaking or potty training) is one of the first things you need to work on with your dog. Crate training can be a very helpful part of the training process. This includes house training as well as many other areas of training: