First off, which thermostat have you decided on? If you havent chosen one yet, I HIGHLY recommend Herpstats and Vivarium Electronics (or VE for short).

So your thermostat is going to have a probe coming out of it to track the temps of the UTH at all times and thats also how it regulates it, so you want to put the probe at the hottest point of the UTH.

So, from top to bottom:

Substrate
Glass
Thermostat Probe
UTH - foil taped or just stuck directly on the bottom of the glass

The thermostat probe should be outside of the enclosure, and it should be placed directly in the center of the UTH. You can use a seperate thermometer with a probe (buy them at any pet store for $10) to measure the temps inside the tank.

Read this tutorial on how to set up a tub, it shows very clearly how to set up the thermostat and probes, and will be the exact same for your glass tank.

http://ball-pythons.net/forums/showt...Basics...*DUW*