My puppy is only a month and 3 weeks and hasn't been eating or drinking anything... she doesn't want to play and is sleeping a lot. She throws up white and yellow stuff and poops brown waterey stuff. What should I do? I don't have money for a vet.

You only have two choices:
1. Beg, borrow, sell stuff to get the money for the vet
2. Watch your pet suffer.
Sorry it is the truth pups that young can go bad so quickly and need help when this ill. Please ask people for loans to help out, sell stuff, etc so you can get your pup to a vet. Also start saving money as your dog will need to go to vet regularly for shots, check ups and emergency visits.

You may also want to try calling different vets in your area and ask if they offer payment plans, if not, ask if they know of any agencies or rescues that help in hardship situations.
Call the local humane society and shelter any agency in your county that has anything to do with pet care.
The bottom line is your puppy needs to see a vet. Young puppies have very little to fight illness with and will quickly dehydrate and take a turn for the worse.
Find a way to take him in or surrender him to someone who is willing to do what you cannot do at this moment.