a tank, to start with............. we used shellgrit for the floor, dish of sea/salt water, somethig to climb up and something to hide under. For food, they are scavengers, and so will eat a few small scraps, but to maintain a decent diet for them wiht all the minerals and stuff that they need, you can buy special food for them.
Good luck, they're fascinating little creatures, and so funny at times.
OH, and you'll need an empty shell, one just a tad larger than the one it's in now, so it can grow into it. I once saw one suss an empty shell out for a while, and was lucky enough to be watching to see it wuickly grab the edges of the new shell, haul itself out of the old one and plonk it's back end in the new one. GROSS! it looked like an alien!!!!