Here is lots of info:
http://www.ifga.org/guppy_beginners.htm
If your guppies bred once, they'll breed again, so you're likely to be overrun with fry at some point. Depending on what else is in the tank, they may eat some of the fry...not a bad thing really, since guppies tend to overbreed. If you want to raise them in a separate tank, a 10 gallon will suffice, it needs to be filtered and kept a tropical temperature like any other aquarium.
If you leave the fry in your current tank, provide some extra hiding places with live plants and just feed crushed flake, micro pellets and other fine foods.