Get your dog to lay down in front of you. Once he is down, encourage him to go to a hip (whichever side your dog favors). Now take a treat, show it to your dog. Keep the treat close to your dog’s nose and move the treat slowly over the dog’s shoulder towards his backbone. Your dog should turn his head to follow the treat. At first you may have to place your other hand on your dog’s back to prevent him from standing up.
The further back you move the treat, the more your dog should twist his neck to follow the treat. If the neck twists far enough, the body will follow. Once his legs are in the air, continue using the treat to lure him all the way over. Remember to label the command with one word such as ‘over’ or ‘rollover’. Be consistent with the command you give every time you work with your dog on roll over. Until your dog knows what is expected by the command, only say it as the dog is doing the trick. Always give him the treat when he is all the way over.
With practice, your dog will no longer need you to lure him all the way over. You will be able to say your command and make a rolling signal with your index finger to cue your dog to roll over.