If the Site Sculptor included HTMLEditor files are installed similarly to other WebAssist products, then adding styles will not be a problem.
There are two select lists in the HTMLEditor instance on your page that help with this, - one is called 'Format', and the other is 'Style'.
The Format box contains H1 to H6, and these can be customised to reflect six headings.
The Styles list can contain styles that you select from your stylesheet. You could also write classes for your headings to appear here if you prefer.
A tacky demo is Here