Sorry - I thought you were asking about CSS Sculptor.
Which version of CSSMenuWriter do you have? There is another newer Guide for CSSMenuWriter 2, which can be found HERE.
Either way, each guide tells you how to get to the tabbed panels. In your MenuWriter Screen pdf that you uploaded with your post, you will notice the 'Define' button to the right of both the 'contents' and 'Theme' select lists. The idea is that once you have chosen a type and style from the ones listed in the selectable lists, you can click the 'Define' button to the right of the Contents select list to define your page links, and the 'Define' button to the right of the 'Theme' select list to fine tune the design of your menu to get it the way you want it.
It is the second of those (Define Theme) which will show you the interface with the tabbed panels.
Hope this helps, - post back if you have any queries,