Becoming agitated, turning round and licking her rear end, scrapping up her bedding (give her newspaper so she can tear it up). First physical sign will be a little bubble emerging, then she will start to push and with luck a puppy will emerge in a fluid filled sac, make sure if she doesn't break the sac that you do. She should start to lick it clean and may also eat the afterbirth. The pup should find its way to the milk bar. If she has not produced a puppy more than a couple of hours after starting to have contractions then get her to the vet as she may have eclampsia or a puppy stuck, same with subsequent births. Good luck, it is wonderful to see if all goes well.