how to discipline a dog.

It really depends on what your dog is doing. I see you have rottweiler in your tags, so I assume that is what breed we are talking about. We just had to have our 12 year old rottie put to sleep 3 months ago. She was a very good dog. If your dog is chewing on something, you need to tell them "no" when you find them doing this & then give them a toy that belongs to them. We bought Kong toys for our dogs & they are very tough & the dogs cannot chew through them. Maybe if you tell more about what your dog is doing, you will get more suggestions.