My hap'worth: Rockscaping is quite hard, and even harder in seawater. The rocks you have are artificial which makes things even more difficult. Suggestion:
- Buy a lot of live rock. It'll survive a few hours out-of-water
- Empty your tank
- Experiment with how the pieces could jig together, outside the tank
- Spread a towel on the floor and on it, build a jigsaw of interesting pieces, figuring how they would fit together in the "big picture"
- Transfer your assemblies into the tank, each building on it's predeccesor
- Re-fill the tank