What base do you use for sea gl?

I am redoing my bathroom, and want to put sea gl on an area of the wall in front of my tub (appx 18"x60"). Just random pieces, no mosaics or patterns. It will be going onto just plain drywall. Is there a special base that I need to use to "stick" it into or do I glue and then grout it? Can I even put it on drywall? Someone suggested it might get too heavy and tear the drywall.