Here is what a I have from our doggie classes:

1. Start with your dog in a standing position.
2. Put one hand under the back legs.
3. Give the command "bow" as you encourage the dog to slide down and back by showing the dog a treat/toy and moving the treat down to the ground between the front paws.
4. Praise & Reward as soon as the dog is in the bowing position.
5. Repeat steps 1-4 until the dog understands the command and can do it without any assistance from you.