Incense charcoal actually has a number of different uses, and its most major and typical use is to heat incense woods, chipped incense, and resins.  Self lighting charcoals used in censers to smolder herbs, powdered incense and resins.  Once a charcoal tablet is lit, they burn extremely clean and they generally last up to about a half hour - one hour each, depending on the size of the tablet.

 Light the side of the charcoal tablets until you see tiny sparks start to appear. Next you want to place a burning charcoal tablet with the indentation upward in a heat proof container that has sand in the bottom, as this will help to dissipate the heat.  Wait until the sparks completely reach to the other side, and then sprinkle a pinch of powder incense all across the charcoal. 

You continue to repeat this process until the charcoal goes out, which will be approximately an hour from the time that you first lit it.