My Cat JUST GAVE BIRTH, WHAT DO WE DO? she gave birth on my bed, she's got 4 kittens.?

2 greys and 2 whites or this is what they seem. They are all moving and nugding the mom's side. One still has the umbilical cord (however you say it) she gave birth on my bed!!! I don't want to move her but she's tired and there is blood and a lot of wetness. Babies are very dirty and so is mom, she's tired, can we help, what do we need?