First off you can simply use the unit to record a ride that you already know. This will let you see on a map where you've been and also see a profile of the elevations along the route.
Second you can down load courses from this sites routes page as well as many other sources on line. Then load the course into the unit using the Garmin program that came with it or an aftermarket program like
http://topofusion.com/ then you can follow said course.
To use the unit on a ride that no one has tracks for. You need to hand draw your own track. For this I would say you need a program better then the Garmin. With a program like
http://topofusion.com/ you can look at several sources different maps and aerial imagery.
Your unit will have some kind of base map already. The one from the factory doesn't have much more then major roads. The base maps you can add, for the older units, is not a real map image but more of a digital representation of the roads and contour lines. Garmin sells their own or you can down load free versions as well. A better base map will help if you need to plot a course out in the field, to say escape from your planned route in case of emergency or break down.
A base map can also help you figure out where you are on a larger map. Plotting a new course just on the little screen can be a pain. Having a paper map and using the GPS to help locate your exact position helps take out the guess work.
Finally there is one limitation of the older units. When storing a course in the Track Log you only have room for 10,000 points in 20 500 point segments. If the track you down load is larger then that you need to use a program to simplify it down to 10,000 points then split it into equal sized pieces for loading into the unit.
Hope this helps.
Tim
PS you likely now have even more questions. Start playing with the unit things will start to make sense. There's a lot to work out but its not rocket science. You'll get there before long. Pick out a program to use on your computer, even more questions, and start playing with that. Once you start to get a feel for things you'll be able to ask more detailed questions. There's lots of good folks here who can help with more detailed answers once your ready.
