What does a good 3-toed box turtle set up look like?

ok so heres the idea, i have a month old 3-toed box turtle, i live in alberta canada, and was wondering what the area should look like, i went to the store and the owner said to have a big, but not to big and have a out 3 inches deap so they can dig, i know what food and water to give them and such, but what should i do, i currently have 18inches by 24 inches plastic container, and i want to know how the set-up should look, also if there is some websites with pctures of 3-toed it would help, thanks.