good to see u got a thermo.... i have 2, 13Watt heatmats, they get into the high 40C's sometimes!!! so i highly recommend a thermostat.
Yea just place the heatmat on the floor of the enclosure... or if its a stickon one, stick it......
then place ur click/clack half over it, then place the thermostat probe on the otherside of the heatmat that isnt coverd, and set ur therostat to 32C. Your done, safe and sound