hi i bought a heat mat today and im not entirely sure on how to set it up i know the basics. probe thermo where i want the hot spot. my question is i have ceramic tiles for it but have no idea where to put them do i put them under the mat on top( then what goes under it) or do the tiles go under the sand in the enclosure. i did a search and didn't find a definite answer. if someone could help me figure this out it would be much appreciated.