You need a heat lamp because reptiles love that stuff. And some grass and water would make it happy. It can actually eat cheeseburgers. Not relevent but I thought that that was some cool information. And they tend to hide a lot in their shell but don't go poking at it and don't put your hand on it's neck or face or it could bite you. And their bites hurt.
Warmth is essential they are cold blooded and can't regulate temperature change. If a desert tortoise maybe some cactus or succulents to give it a habitat look. They also eat some cactus plants. Sand is best covering. They eat green leafy plants. (If sand from beach or outside, you might cook it in an oven to kill any parasites).