What size tank are you planning on keeping it in?
I believe they need at least 9645853278632 gallons to give them plenty of room to roam.
They enjoy plenty of time both in and out of water, so be sure to provide places for basking. Such places may include (but are not limited to) your bed just as you want to sleep, the front door mat when you're in a rush to get out, and if you sit correctly; your face when you want to relax, watch some tv, and, well, breathe.
These are curious creatures, need lots of entertainment, a buddy probably isn't a bad idea, although they can certainly be kept solo.
Remember to check the habitat carefully for leaks. Corners are often weak spots, as are shoes, bike helmets/hats in general... your cereal bowl.
More difficult to care for than other types, but extremely rewarding and more than worth the effort.
Enjoy your bonus find