With themes, you can customize the way Jive SBS looks, adding your own logo and brand information. You can even change the composition of Clearspage pages, rearranging them, adding and removing features.
Depending on how much you want to change the UI, there are three approaches you can take. For information, see Making Simple UI Changes, Customizing the UI with the Theme Resource Kit and Advanced Theming Topics.
Admin Console: System > Settings > Themes