How do I care for newborn rats?

Well my rat had a litter of babies yesterday but then today when I woke up she was dead! It broke my heart so I don’t want her babies to die what should I do? What can I feed them? How do I feed them? How often should I feed them? How do I tell when they are full or still hungry? Please I need help what should I do? Please give me as much info on taking care of baby rats as possible I’m very desperate at this point! Every article I find on google does not help at all it doesn’t say anything about how to care for a newborn rats only like a few week old rats!!