Navit comes with a sample map of Munich, but if you live (or drive!)
anywhere else, you'll need to add another map set. These are not
available as packages because they're rather large and the data changes
on a daily basis, so the packages would have to be refreshed very
often. For instructions on downloading or generating, and installing,
different types of map sets, see these Navit Wiki pages:

http://wiki.navit-project.org/index.php/OpenStreetMaps

http://wiki.navit-project.org/index.php/European_maps

http://wiki.navit-project.org/index.php/Garmin_maps

You should either add the appropriate configuration elements to
/etc/navit/navit.xml, or copy /etc/navit/navit.xml to
~/.navit/navit.xml and edit it there. You may have to remove or comment
out the section for the sample map set, also. Also note that the
default configuration assumes you have a GPS device active, and gpsd
running.