For each portal instance, you can explicitly manage the navigation tree. We will see how to create new nodes for the navigation tree, select the page instance for the navigation node, and change access permission on-the-fly.
In order to manage the navigation tree you need to know that each navigation node must be associated with a specific page node.
We discussed in the Managing portal pages recipe that while creating a new page, the portal automatically creates a navigation node for the page for showing the page in the portal structure.
The navigation structure will be rendered in a different way for each user based on the user identity and group memberships.