The term "Live Rock" simply means that it has beneficial bacteria on it and inside the tiny holes, nooks and crannies.
You have Dry Rock right now. So? All you gotta do is put it in the tank and drop a cube of food in there. Let the food rot. Let the tank sit for 2 months. This is the cycle you'll need to go through in order to start the tank again. No big deal.
Now you got Live Rock.
People have this idea that live rock is complicated or special. Live rock is nothing more than ROCKS. It just happens to have sat in the tank long enough for the bacteria to begin growing on it.