1) Go to the main page of this website (click the "Home" tab above this thread), and read the sections on "Social Life" and cages.
2) Go to the Nutrition thread and read the recommended diet posts here and here.
3) Be sure your guinea pig has good timothy hay all the time, good pellets without colored bits and seeds in it, and plenty of water.
Guinea pigs like to live with other guinea pigs -- they're very social animals. You need to think about getting two, or else get a pet that doesn't want a friend, like some varieties of hamsters.
You also need a vet fund -- vet care for them is expensive, because regular vets don't know much about them.
Will your parents be helping you with your baby's care?
Hi and welcome. Please read threads here in the forum, especially nutrition charts, baby-proofing a C&C cage, etc. Then post any specific questions and we'll try to help out !