Are you sure that is not a thermometer? What you have looks like one of the "stick on" thermometers from petsmart or petco. What you need is a digital thermometer/hygrometer and a digital thermostat. I like the ones from walmart that are called Acurite thermometers. They work wonderfully and you can't beat paying $9 for one. It includes both a thermometer and hygrometer.
http://www.walmart.com/ip/Acu-Rite-I...mometer/896347
A thermostat is what you plug the actual heating pad into. The heating pads can get dangerously hot and the thermostat ensures that the heating pad does not get too hot by shutting it off at a certain temperature threshold.
I will always be a fan of herpstat thermostats.
http://spyderrobotics.com/home/products.html
You can also use a hydrofarm thermostat, those tend to work well too, but if you have the money I would definitely buy a herpstat.
This guide is very helpful in showing you how to place the thermometer and how to set up your glass tank http://ball-pythons.net/forums/showt...-With-Pictures!
I have a 40 gallon breeder and it has been perfect so far.
As said before he probably will not eat because the tank may be too big for him and the tank does not seem very secure for his hiding purposes. Is there a temperature gradient at all?