You could manually edit the navigation template, and add your own tabs.
Or you could use a plugin to add your own tabs to the navbar.
I made a plugin that quickly lets you add tabs without having to customize the navigation or know any xenforo template code; http://xenfans.com/threads/xenfans-com-extra-tabs.1435/ I could give you a login to my site if you're interested.
In the above situations by default any node page loaded keeps the Forum tab highlighted.
Dont' worry about it. It's a learning process and if the support team doesn't answer, there's a huge community here that can help. Everybody is new at this at some point, and those who learned a bit are helping others with the same questions.