First of all, what kind of fish just had babies, and how big is the tank they are all in? I'll be able to help you once I know more
Baby fish (fry) should be in a big tank to they can grow properly (5 gallons minimum, 10 gallons preferably). They should be fed fry food: either liquid food (which may cloud the water in your tank), or flakes (crushed as finely as you can). 3 times/ day is ideal.
They need lots of hiding places to survive, if you are keeping them with the adult fish. This is so they don't get eaten. If you have a filter in the tank, they do not need extra oxygen.
Depending on what kind of fish you have, the mother/ father may eat the fry. You should seprate the fry from the parents if possible.
Once the fry are several months old, and big enough to not be able to fit in the parents' mouths, they are ready to be put back in with the parents.
HTH and Gl with your new babies
P.S. Maybe a Mod could move this to the appropriate location?