Looks like this is a hot topic lately and a bit confusing for the new DreamWeaver users. I will show you how to slice up a basic content box and use DreamWeaver to create the tables and format the box to accept content without displaying a mess whenever the content is too much or the size of the browser window is changed etc...
First off, I will use Corel Photopaint to slice up the content box, but you can certainly do this in any graphics program, including Photoshop or even MS Paint.
Here is the content box I made: