Newborn puppies are just as fragile as newborn humans. Maybe even more, considering they can't even see the world around them -- they're born with their eyes closed. Caring for tiny pups can be a challenge, especially if you're not used to it. For example, most people don't know that you shouldn't pick up and cradle newborn puppies to sleep. In fact, your should handle them as little as possible.
Keep your participation to a minimum. Ideally, mom should be the one caring for the puppies. with you acting as a sort of support system. If the puppies seem ill or if mom is having a hard time with the situation -- for example, if there are more puppies than nipples available -- then you should step in. But pay attention to what's needed so you can help without being too intrusive.
Provide a soft, warm, safe place for mom and the pups. Some towels, a thick blanket or a flat dog bed would do. Newborn puppies need to stay very warm to avoid getting sick. If the weather's not helping -- or if the puppies are orphans sleeping alone -- wrap a towel around a hot water bottle and place it on the puppies' bed. They'll probably pile up on it to enjoy the warmth.
Pay close attention to the pups' eating habits during the first few days after birth. If one pup seems to be getting too little milk or has trouble eating, you might need to bottle-feed. A vet can teach you the proper technique and tell you which milk replacement to use. Be ready to feed every few hours -- and yes, that means getting up during the night, just as you would with any newborn.