FOXY,
Let me start by saying you have made a good choice! My Ball was my first snake, and they are *excellent* beginner snakes. I shouldn't even say beginner; they are excellent no matter what! They are easy to care for, and have wonderful temperments. It helps that they're cute, too.
What do you need to start? Well, we have a Ball (our first snake) in a 30" L/12.5" W/13" H tank. She is 8 months old; about 26" long. I think this is a 20 gal. terrarium if you're talking gallons. It is still just fine for a Ball her size, but we will need to get something larger in less than a year.
For substrate, we use "decorative bark," small chipped bark, which is available from local hardware stores. You can also mix the substrate with some Peat (Sphagnum) moss, maybe 20% moss and 80% bark, and then spray it down every day or so to help keep the tank between 50 and 65% humidity. The moss holds moisture longer than the bark does.
For heat, we use a self-adhesive under tank heater, and also a ~50w red bulb overhead. This helps keep temps between 79 and 86 degrees F (cool and warm side).
Throw in a hide log, a water dish, and some plants...you're ready to go! Enjoy the Ball!
PS...they seem to like to climb a lot when they are young, so try to get a plant that will support his/her weight! It is hilarious to watch our Ball still try to get into her plant, because she is too heavy for the little plastic branches!