OK Mike, here are some schematics.
The idea here is to place your big rocks on the bottom and smaller on top. You want to be sure and push the rock down to the glass. This will keep your aquascape stable and prevent it from shifting in the future. Also, think caves! Don't stack rock tight on top of others. Try to stagger the rock and make open spaces. This will make the tank look fuller and give room for the fish to play hide and seek.
Do not stack the bottom rock against the glass. Bring them into the open and 4-6 inches from the sides. Let the upper layers of rock lean against the back glass if necessary for support, but try to avoid it if you can.
Remember to stack rock upwards. Ideally the highest points should be 6-8 inches from the top of the tank. This design is taller on the left than the right side.
This is a very nice design that you should have plenty of rock for. Save the largest rock for the right side, single rock island. On top of this island place your nicest coral, or in the future buy a nice coral on a rock and stack it here. On the left side stack all the other rocks. The red is a base layer, the black is midlevel, and the blue is upper layers.
This is by far my favorite design, but you need a wide tank to do it. I tried to do it in my 18" wide tank and did not have enough room. But, I use very big rocks.
