The newest version of Offroad Navigator (v2.2) only has "file' as an option to load up a route (at least this is true on my TomTom). The older version(s) of Offroad as I recall, did have "favorite" as an option although I never did use that feature.
If you want to set up an itinerary (.itn) route using roads, using Favorites, here is what I would recommend - it works great for me:
1. On your TomTom Add Favorite, Point of Interest (or address, Latitude/Longitude, etc). Repeat for each Favorite you wish to include in your 'trip.'
2. On TomTom Itinerary Planning, Options, New Itinerary, Add, Favorite.
3. Keep adding Favorite(s) until finished with Itinerary.
4. Choose Options, Save Itinerary.
5. Itinerary should appear on File button on Offroad Navigator.
If you want to set up an offroad route, using Favorites:
1. On Google Earth zoom in to get exact coordinate(s) and write them down.
2. Open up TomTom (easiest to do this with Home pgm) and add these coordinates as FAVORITE places.
3. On TomTom, create a new itinerary using these Favorites as Waypoints.
4. Save the itinerary
Good luck!