Adding Custom divs using CSS Sculptor 2.0
Take a look at the Adding Custom divs using CSS Sculptor 2.0 How To found on the CSS Sculptor Support page.
Hover over Support > Choose Eric Meyer's CSS Sculptor, then expand the How To's section.
Or click this link: csss2_adding_custom_divs_ht.pdf
This provides a generic introduction to adding custom divs, and should give you enough information to achieve the result you are looking for.