Anyone with tips for stacking rocks?

[Complexity]

I can post pictures later. Right now, they're still in tubs in the car. I need to sort out what I got, then that'll be a good time to grab some pics. I hope to get that done this afternoon.

[myjohnson]

Can you post pictures of the rocks?

Depending on size, but generally I wouldn't use the back glass as support.

[Complexity]

I got my tank yesterday, and I'm working to get it set up. I have a plastic grill for the bottom of the tank.

The rocks I have are extremely heavy! And I want to stack them pretty tall. I intend on first putting down the grill, then stacking the rocks, and then adding the sand. I might put some sand in places as I go, but the idea is to make sure the rocks do not have sand underneath them so that the rocks can't fall when the fish move the sand around.

Other than that, are there any hints or tips for stacking the rocks? I'm a bit scared since the rocks are so heavy, and I can't even touch the bottom of the tank. I tried to get a few large, flat bottom rocks for the base of the stacks.

Is it okay to have rocks touching the glass in the back? Can I use the back glass as a support at all? Or do I need to keep the rocks completely away from the glass?