To care for a Guinea Pig (also known as cavies), please see the following websites.
In addition, some critical points are:
they need a lot of space to run around, so a small cage is cruel
they enjoy a companion, best to be of the same sex to avoid many babies
they need to eat Timothy hay as their main diet - there are special Guinea Pig pellets as food supplement (about 1/8 cup per day)
they need a source of vitamin C (for example, a quarter of a green or yellow Bell pepper without the seeds)
How to introduce guinea pigs