I am a complet PC numpty but it's quite easy. I taught myself thro' trial and error mostly.
It does it automatically, storing the each day's journey in 'Tracks' which you can access via 'My data'.
You can either save them as Routes, using the device itself, or export them to a PC (or another device) as GPX exchange files. You may find leaving them as Tracks is easier, particularly if you want to manipulate / edit them by tracing. If you are confient using editing in the Route ot Track Properties view then it doesn't really matter what you do.
If you have lots of Tracks saved on the device it may start storing them in a special Archive folder, which does not export to your PC automatically. It is easy to find using the 'Computer' option on your PC, then clicking on the Garmin's drive, then on the folder called (I think) Garmin, then on anything that looks like Tracks or Archive.
As Tracks are GPX files they will not open up automatically on your PC or in Mapsource. Change the Mapsource option (bottom right of the Mapsource screen) to 'All files' or 'GPX'.
Using Route tool, it is easy to trace over Tracks in Mapsource, converting them into Routes, so you can correct any errors. Just take care that you zoom in quite a bit or you will miss the road (the GPS device is only accurate to about 15 metres) ending up with a lot of waypoints which will jumble up your favourites.
Have a play before you go. You can't break it.
