How do I edit my main navigation bar?

Hello,

I am the manager of my Jive community and am having difficulty editing the main navigation bar.

I believe you should be able to edit the nav when customizing your site (see picture below), however I cannot find any option to do so. The version I am using is Jive SBS 6.0.1.1

If anyone could provide some guidance on this, I would greatly appreciate it.