I don't want to come across as rude, but if you haven't researched everything before you set up, you should at least be researching one step ahead of where you are. For example, researching what to do with the rock before you buy it, not after. I'm hoping you've rinsed it off or scrubbed it in a bucket outside the tank.
I'm not sure if you're asking about aesthetics of the aquascape or practicalities (such as where to use what size of rock, how to stack, etc.).