This will be the navigation 'column', which will run down the left of the page.
And this will be the main content block. I have not used another HTML tag beyond the div tag on this page to lay it out. No tables, no transparent images; just divs and style commands.
This layer may look like a table, but you may notice that it is positioned above the layer to the left.
And yet another layer goes above the main content.

Notice the tasteful border.

I could go on, but I think you see the brilliance of these things.
Make sure you view the source of this page to properly understand what's going on here.
Now, try resizing this window by pulling the corner. The layers will move around as the page sides get closer to them, because they are positioned on the page relative to its edges, and can react if those edges change.

And here's some words. This text comes last in the code, but appears top of the page, as there's 'nothing' above it.