They mature quickly compared to other fish. Keep them warm with a low flow filtration, feed them crushed flake food, just pulverize it between your thumb and forefinger. Keep the water clean. Sell what survive to a LFS if you can. If you dont want the babies just leave them in with the parents. Keep all one sex if you dont desire any more fry, or a ratio of 1 male to 3 female if you want tons more babies. Once you can sex them seperate males from females to prevent more unwanted fry, or like I said before leave the babies in with the other fish, even with that some will survive.

Here is a link that might be useful: General Breeding Info for Platys