I know there are mods for having multiple navbars, so have a look around in the mods section.
As for changing the navbar:
Go into your AdminCP. In the left column, choose Styles & Templates/Style Manager. This will bring up a list of all of your forum skins. In each and every one, you will have to expand the options, find either the header or navbar template pages, and edit them. The code you are looking for looks most likely just like this:
Code:
<td class="vbmenu_control"><a href="usercp.php$session[sessionurl_q]">$vbphrase[user_cp]</a></td>
Just change the $vbphrase[user_cp] (or whatever you are changing) to say what you want, and the usercp.php to the new link place (like forums.php, or rules.php). If you are adding instead of changing, just copy paste the original code in the place you want it and then change the variables.
I'm self taught for the most part, and that was one of the things I've had to do a million times because of the sheer number of templates and my insane need for Home, Forums, and Rules buttons. XD