So that's above the coals then on the shelf on a little tray is best ???
See pic of where you put coals - was using wood for pizza's - the other shot shows the location of the cooking area which is just above that where I guess you put the meat ? What TBJOEBBQ is saying is build your fire on your fire grate, but off to one side. Then you place your meat on the same grate that the pizza stone is sitting on but on the other side of the chamber so that it is not directly over the fire. You can then place a pan of some kind under the meat so that when the juices and fat cooks out, it won't fall into your ash pan and be hard to clean. You can then also use those juices to add back to the meat, or if you cook beef roast make an au jus sauce.
Also a lot of recipies suggest mustard on the outside - we authentic get Fench's Classic Yelloe over here - that okay ?? That is fine. The mustard is only to help hold the rub in place. You shouldn't taste the mustard after it is cooked. Some claim it helps enhance the bark, never tried it myself.