Hi, Jerry. You want to insulate between the joists. The rafters are up in the attic. and the paper goes down. You want to keep humidity out of the insulation. At least this is the normal way in most parts of the country. You might double check this with a local insulation contractor in case there are some local conditions where it has long been proven that "the wrong way" works better.
You should also install a vapor barrier over the sand. Get some 6 mil or heavier poly at the home center and lay it down. If you have to use more than one width, overlap by a foot or more. Then throw some gravel over the poly sheeting to hold it down. This is easy and inexpensive.
Do you have ventilation, and preferably cross-ventilation in your crawl space? You should have a minimum of one vent per 250 sq. ft. of space. The vents should have a grill opening that will keep any critters out.