Well, that gerbil tail thing is just weird.

I recommend Flexwatt from http://www.reptilebasics.com/. Get something that will cover 1/3 to 1/2 of the bottom of the enclosure (probably 1' of 11"). Also get the $5 clips and ask them to attach them for you. Tape it on to the bottom of the enclosure and plug it into a THERMOSTAT (very important). This is what I'd recommend. Put the probe between the UTH (yes, under tank heater) and enclosure and use a digital thermometer with a probe placed inside on the glass directly above the UTH to set the thermostat temp.

I guess recommendations change depending on your location, but that's the general setup.

You really need to find a vet even if it means several hours driving. It's better than nothing in an emergency.