Views are used in NorthStar to allow tracking netblocks that are used more then once throughout a network. This feature is most often used to track multiple locations that are using private address in more then one physical location. To access the views administration section click on the 'Manage Views' link in the leftmost menu of the NorthStar screen.
To add a view click the 'Add View' link in the top right of the view listing. Fill out the values on the form that loads and click the 'Add View' button. Your view will now be available in the 'Select View' box when adding a new network.