As other have said, it's a Red-Eared Slider. If it really is a female, you're gonna be needing a big tank soon, I think the accepted minimum for a female is something in the family of 75g? Not to mention they need a heat lamp, basking platform, and a large amount of UV. I'd lose the substrate, they crap a LOT, and I find that with aquatic animals, gravel makes it harder to clean.
