I hope your dog isn't in labor right now, if it is, why haven't you done more research on labor and pregnancy in dogs in the last two months that your dog has been pregnant?
If your dog strains and no puppy comes out in an hour, call an emergency vet. Otherwise let things travel at their own pace unless the dog isnot doing anything with the puppies when they are born, IE, licking them clean to stimulate breathing and movement, biting the placenta, etc. If that's the case get some clean towels to rub the pupppies clean and call the vet as well to walk you through it all.
Most first time moms don't know what to do. My blue chihuahuas first litter she had no idea what to do besides push. I did the rest of the work for her (cutting the cord and disinfecting it and most importantly breaking the bag over the puppy's head). By her second litter she had a little better of an idea what to do but I still would have never left her to do everything on her own. After the pups came out she was trying to pull the placenta out and too much pulling can cause a hernia on the puppy's stomach. What breed? Is this her first litter? What day of the pregnancy is she on?