Actual GPS Satellite Position + Pre-Recorded Track + Topo base map = route following magic
I am not a GPS expert so I might not use the correct ‘terms’ but here is what works for me (of course there probably are other ways to accomplish the same tasks). Oh and sorry if I am explaining stuff you already know…….
1: Download the relevant sections of a topo base map to your unit (Garmin TOPO US 2008 is what works for my eTrex unit, I assume it’s the same for your unit, not sure if memory is an issue for your model)
2: Download or ‘make’ a “Track”, on/to your PC. (see the Routes page for lots of GPS data/tracks on this site) You can then transfer/upload the track to your unit. Garmin Mapsource can transfer a Track to your unit but I use TopoFusion as it works much better imo.
3: Practice a bit ‘following’ a real track (you might make one up for a local ride as a good training/familiarization exercise)
Comments/Notes:
A Track “lays on top of” the Topo base map and the Track (route) should ‘match up’ to the roads & trails on the base map. Your unit can also ‘record’ a Track while actually riding a route, this is where many of the best Tracks came from originally. But of course recording a track as you ride is basically only good for generating a Track for future use.
I make/modify/check most of my Tracks with TopoFusion, I highly recommend this program. I only use Mapsource to download sections of the base US Topo map to my eTrex unit. I sometimes use Google Earth to make a Track but it takes a bit of work to do so. I do use Google Earth to ‘fly’ the Tracks all the time, it’s fun and very informative.
I also did a bit of hiking with my dog and Geocaching
http://www.geocaching.com/ along the way to familiarize myself with many of the GPS features including how to follow tracks. At first it’s easier to ‘play’ and experiment with the GPS on a hike vs a ride.