Checkout this thread, it goes over cage heating in detail:
http://ball-pythons.net/forums/showt...t-Thermometers
Your snake needs heat 24/7 (90 degrees F on the hot side 80 degrees F on the cool side) I would suggest getting an infrared heat bulb as they can be used 24/7. White heat bulbs stress BP's out and shouldn't be used at night.
Here is a good infrared heat bulb: http://www.petsmart.com/product/inde...uctId=11147193
The rest is covered in the thread I linked above. If you have any questions feel free to ask!