The CSS Sculptor tool will allow you to create a new CSS Layout and produce a page from this layout. The pages that are produced by this tool are not re-entrant, they are just the output of the tool.
The idea is that you do all of your editing for your layout within the tool and then create a page from the layout and save a preset for it. This way if you ever need to create that page or change the layout you can do so from within the CSS Sculptor interface.
Please post back with any specific questions that you have about the tool or if you run into any problems.