With your dog sitting at your side, set off and give the command “heel” (so that your dog is aware you are about to move). If the dog gets ahead, stop and encourage it back to your side with a titbit. Repeat. To begin with, stop every three to four paces to praise your dog and give a titbit. Do not use your voice unless your dog is at your side. You can also practise this off-lead in a secure area – this makes you work really hard at keeping your dog with you, rather than relying on the lead.
There are a lot of different ways to train your dog. You may choose to sign up for a dog training class, hire a professional dog trainer for private lessons, or even send your dog to board with a trainer. However, plenty of people successfully train their dogs on their own. It's a great way to save money on training costs, and a wonderful way to bond with your dog.
Just because your new dog is old enough that he should know where to potty doesn’t mean that he actually does. An adult dog has the necessary muscle control to hold it for longer periods of time, but if no one ever taught him the potty training rules then he’s the equivalent of a brand new puppy. Age should not be equated with housetraining prowess, so it’s a good idea to treat any dog new to your home as if he’s still learning the potty training ropes.