you will first need to save the CSS Sculptor design as a Template.
See the "Creating a custom template for Site Sculptor" tutorial on the Site Sculptor Support page:
once you have created the template, and added the necessary editable regions to it, you can create a new site sculptor design from the template using the Preset Manger.
go to WebAssist -> Preset Manager. From the product list, select "Site Sculptor Site Design" then click the New button