Sit is a good starting point for training your pet. The sit command is simple to teach and is a good command for your dog to know. Sit can end a lot of behavioral problems your dog can develop such as jumping up on people, running away when they are outside, and running outside when you open your door. Sit is also good to teach your dog because lots of other commands can be taught from the sitting position.
To teach your dog to sit, kneel in front of your dog so that the two of you are facing each other. (Anytime you are doing an action trying to teach your dog something make sure you repeat your dog's name and your command word over and over again.) With a treat in your hand, put your hand a few inches in front of your dog's nose so that you get their attention. Take the treat upward and back over the top of their head. This should get your dog to sit down; enabling them to stick their head straight up and follow the treat. If your dog does not sit and instead backs up, you probably took the treat too far over the back of their head or moved it too fast. Try it again from the beginning, pulling the treat more upward and less over the back of their head and at a slower pace. Reward your dog once you have gotten them to sit. Give them the treat and lots of love and affection. Make it apparent that they sat properly and behaved in a way that is acceptable. Speak in a happy voice repeating "sit, good girl/boy" and their name.
Repeat this process several times, repeating the word "sit" or whatever trigger word you have chosen. After several attempts your dog should begin to sit on command without having a treat in front of them. The use of the word "sit" should begin to be sufficient by itself. Continue giving your dog treats and love every time you get them to sit. If this technique does not work, don't worry there are other ways you can teach your dog to sit.