Instructions
  1. Unzip the map file that you downloaded from this site. You will have a file called gmapsupp.img.
  2. Insert your SD-card into your SD-card reader. If you don't have an SD-card reader you can connect your Garmin GPS to your computer with a USB cable. Make sure that the SD-card is in the GPS unit before you plug it into the computer.
  3. Open the SD-card with the file manager. If there isn't a folder on the SD-card called Garmin, create one.
  4. Copy the gmapsupp.img file into the Garmin folder on the SD-card. (Note: The map will not work if you put it in the Garmin folder of the GPS device itself; the map file must be placed in the Garmin folder of the SD-card.)
  5. Safely remove the SD-card once the file has finished copying.
  6. Turn on your Garmin GPS with the SD-card inserted. Go to Tools -> Settings (the wrench icon) -> Map. Touch the Map Info button and check the box beside the OSM map to enable it. You should also disable the built-in map if areas overlap.