"z-index", How do I use it properly? Options

[kthxdie]

So I've got the image I want as the DIV overlay.

Now, I'm assuming this is the best method, I'm looking to place all the junk on top on the image using z-index values.

I assigned the background a z-index value of 1, and the content a value of 2. But still, my content is not showing up on top of the image.

Any ideas as to what I'm doing wrong would be greatly appreciated.