I will assume you do not have any thermostat to regulate your heat?
1# Make an appointment to a vet asap.
2# Go an get a dimmer switch at home depot or lowes http://www.lowes.com/pd_70717-539-TT...mer&facetInfo=, this will help you control your temps temporarily, while you are placing an order for a reliable thermostat.
3# Remove all the substrate in your tank clean it up and replace it with clean paper towel.
4# Limit stress no handling no feeding until your animal is seen by a vet.
Vet is mandatory given the extent of the burn.