Teaching your dog to sit, stay, and come when called can. Some dogs are more driven by food than others. It doesn't really matter whether or not you choose to use food to entice your dog into learning a behavior, as long as it doesn't become the reason they behave. If you choose not to use treats to train your dog, you can also use a favorite toy or good ol' fashion praise. Sitting is not a new behavior.
Dogs learn to sit all by themselves.
The trick is to teach them to sit when asked. Get your dog's attention by calling his name and praising him when he responds. While your dog is standing, hold a treat or a toy in front of his nose, but don't let him take it. He'll follow the treat with his nose. Don't raise the treat too far up or he'll jump for it.