What do you feed a dog who just gave birth to puppies and I need help?

My dog gave birth to puppies today and I don't know what to feed her now. And how do I take care of newborn puppies? She's a black labrador retriever and gave birth to a litter of four. Is this normal? It's going to be a little chilly tonight. Will the puppies freeze to death? Or will my dog naturally keep them warm? Please give me basically a newborn puppy guide and a just-out-of-pregnancy guide.