Main navigation and sub navigation question

[eluser]copernicus[/eluser]
I searched the site and couldn't find a concise answer to this so,

I have a site with a main navigation:
Home About Projects Contact

And some pages have a sub navigation under the main one, for example the About page has:
Home About Projects Contact
|
FAQ History etc...

How would I make it so it would appear to be a "child" of the about page? So the URL would be www.mysite.com/index.php/about/faq

All the pages are being pulled out of a database and I am using one main controller with a view template where the main content is being pulled from the DB.

Thanks