How to give labor to a dog?  

Unless your dog is a very small dog, Mother Nature will take care of everything, you need only stay calm, keep the dog calm, make sure she is in a quite, saft place and keep the excitment away from her. With each pup you nee to see that it is breathing, Mom will clean the little fellow up and that also helps him to breath.
If Mom is not cleaning puppies, you do it be gently rubbing with a clean cloth. If not brething you can puff into the pup's mouth to get it started. You may loose a pup, especially if it's a large litter, not to worry Mother nature is just taking care of business, any pup you loose may very well not have lived anyway.

If you are worried or have a very small dog arrange to take Mom to the Vet ahead of time for professional help.

Dog births have a high percentage of being very normal and needing very little help from humans.