Injader uses Navigation Types to display three sets of navigational links on your site. Each area can be set as Primary, Secondary or Tertiary.
To see a working example, go to The Guide to Blogging.
The links in the red bar (Home, How to …) are the Primary areas. The links under “Navigation” in the sidebar (The basics of running a blog, and so on) are the Secondary areas.
Unlike subarea links, where the links change depending on which area you're in, Primary, Secondary and Tertiary links will stay the same no matter which area you're in. So you could have your Primary links in the top navbar, Secondary links down the side, and Tertiary along the bottom. It's up to you how you place them.
Click on the Areas link in the Control Panel. From there, you can use the three links at the top (Primary, Secondary, Tertiary) to see your current areas, and the links on the right can be used to add a new area. You can also edit an existing area.
On the create/edit area page you can choose the navigation type and the parent area. This is how you set up new navigational areas.
The Theme Development guide includes some code on how to display additional navigation types in your theme. The default theme includes this code too.