Showing the dog he is wrong , can be done through over emphasis in tone and body language and being very insistent about your point. The dog must know that he is wrong for a change in behavior to begin. The flip side of this, the reward of your own personal interaction, is most important. Gooood Booy ,with lots of emphasis , can be your most rewarding motivation. This takes conditioning though and time to build your bond with your dog.
Timing is also important , because right now is all that matters to the dog.
If you can not make your point in the present , you can not communicate with your pet. Owners must be willing to be consistent during early stages of life , to receive the benefits in the long term or after the dog has matured. Remember too, that even treat trainers must correct or make the dog do the task, when the treats run out or they become full. Our society seems to look for the quick fix on everything now. Immediate gratification is not always the best reward for long term results.