Summarize:

You can use a plastic or metal trash can.  An empty wooden or metal barrel would also work well.  Don’t use galvanized steel cans, which will rust.  A black can will provide added warmth to the soil. If you live in a hot area where the potatoes will get full sun, don't use a black can or the soil could get too hot. If your potatoes are to grow, they need about six to eight hours of sunlight daily.  To ensure your potatoes get the necessary amount of sunlight, you could place the trash can on a rooftop, in an open field, or in a sunny backyard location.
Use a 20 to 32-gallon can. Place the trash can in a sunny location.