Fran,
Bill plans the trip in the computer and downloads it to the GPS unit with the USB cable. We have never downloaded the map from LighthouseFriends and Bill doesn't understand how to use the coordinates but he does use their map. If there isn't an address available he'll enlarge the map and use the nearest roads to program the location. It's probably not real sophisticated but it works! We've been all over and very rarely have we gotten lost or missed a lighthouse. We like having the portable one since we can use it in either car and it is easier to program it through the computer.
Judy