When you are done with the mapset selection, continue to the Join section.
Specify the Output File( name it gmapsupp.img), and key-in the Mapset name of your file to be created. This mapset name will be displayed under each of the map name when you list your maps in Map Info function of your Garmin GPS.
Click the Join all button, and the combined mapset will be created. You can then copy the new mapset file to your Garmin's internal storage or in Garmin/SD card.
if you have multiple maps on a gps-you can't display two maps that cover the same area at the same time-one will have to be deselected