Command - Sit!
Teaching the sit command is best done before any other command. It is easier to teach by itself and not in conjunction with any other activity.
Teach this in the house where ever the dog feels comfortable. The easiest way to introduce the command is with treats. So have a good supply of small treats, kibble, or suitable reward treats. These should be something your dog loves to eat, small finger nail size, and does not get often. DO NOT give this treat for anything else but a reward in training. It' should not be used a general dog treat. (The best treat I've found is hot dogs boiled with a teaspoon of crushed garlic for ten minutes, boils off any fat. One hot dog will yield a dozen treats/rewards. Never have seen a dog that doesn't go squirrelly over them.)
Stand in front of your dog with the treat in your right hand, hand below the level of her chin but in front of her nose, so she has to look down to see it. Don't let the dog lunge for the treat, fend her off with your left hand, If necessary hold the collar with the left hand so she can't lunge or back away. Lift the treat or reward barely over the dogs head toward the middle of the ears. Too high and the dog will try to jump to get it. The dogs head will lift to follow the treat and as you move the treat towards the ears the hind end will lower.
You want to exaggerate this motion with your hand. So that your fingers holding the treat go from down to up. Why you ask? Because later you will use only the motion of your hand to make your dog sit at a distance without a verbal command.
As the hind end lowers say the command "Sit!" Remember, it is always the dogs name first with the command. As soon as the dogs butt touches the floor give the treat/reward immediately. You want to ingrain the contact with the butt on the floor with the reward. As soon as the dog is finished the treat give your release word as the dog moves from the sit. You're killing two birds with one stone. Teaching the SIT and the release at the same time.
If the dog absolutely won't lower the hind end. Kneel beside the dog, hold your hand on the collar and as you raise the treat/reward, slide your hand down the back and cup the base of the tail. This will cause the dog to sit to protect it's hind end but she should be interested enough in the treat that she won't take her eyes off it. As the hind end lowers give the command "Sit!" as the butt touches the floor give the reward immediately.
Still won't lower the hind end? Same procedure instead of cupping the tail, apply slight pressure at the base of the tail. Never PUSH on the hips. The dog will automatically stiffen the legs to avoid lowering. You want to encourage, not force. As the hind end lowers give the command "Sit!" and as soon as the butt touches the floor give the treat immediately. Remember give the release command as soon as the dog is done and starts to move.
Note the emphasis on immediately! This is very important. You want to totally ingrain the contact of the butt on the floor with the reward. Sooner or later the light bulb will go off in your dogs head. "Ahhha when I hear SIT and my butt touches I get that luscious delectable wonderful treat," and that is what you want to achieve.
It should only take three or four successes in a row and your dog will get the idea. It may not be perfect, but you shouldn't be having to cup the tail or encourage the hind end down. Repeat until you get a minimum of six success in a row. Always quit when the dog has succeeded. Nothing succeeds like success. One success as an end note is better than five success and a failure and stopping there. If you only get one success quit there if you have to.
Repeat the procedure as often as you can find the time. Go through the "Sit!" process a dozen times in each session for a minimum of 3 or 4 sessions a day. Do this BEFORE you feed your dog so she is hungry and really wants that treat. That said, you will find if the treat is sufficient, hunger doesn't enter into it.
By the end of three sessions your dog should recognize the command .... when she is in front of you, when you have a treat, and when she feels like it. Getting the dog to sit without the treat, when you want, where you want, is different. So....
Take it outside and do the same training. Do it while walking your dog or playing. Pull out the treats and train the sit exactly as you did inside. The ground, grass is different than the floor in your house and the dog may not want its butt on the grass or gravel. It does take training. Repeat in different situations, in different places, different surfaces,
Limit the reward. Only give the reward every second sit. Then every third sit. Give praise, pats, pets, and ear scratches instead of the treat, but have the treat available just don't give it to the dog every time. Limit when you give the treat, but never limit praise. Vary when you give the treat. Give a treat three times in a row then don't give it for five, then give the reward then don't a few times. Make the reward totally random.
The major flaw in treat training is that dogs aren't stupid! The know when you have that goody. You say sit without a treat and all you've done is treat.... Your dog will look at you like "yeahhhhh right." Discontinue food treats as soon as possible! When your dog KNOWS the command start eliminating them very quickly. Praise, pats, scratches, belly rubs and HAPPY are the best rewards you can give your dog. When you, the BOSS is happy, your dog is happy out of her furry little body.
Plus it's not fattening.