The Garmin Nuvi receiver provides navigation, maps and directions from a global position satellite. Even though the device comes preloaded with maps and points of interest, you can add map files to the Garmin Nuvi as needed, from either the Garmin's internal memory or from an additional MicroSD card.
Insert the microSD card into the memory card slot on the side of the Garmin Nuvi.
Connect the miniUSB end of the cable into the port on the Garmin and connect the other side of the cable to one of the USB ports on the computer. The MicroSD card will appear as a removal folder icon on your computer's desktop.
Locate the map file on your computer. Right-click the file and choose "Copy" from the context menu.
Double-click the folder icon for the MicoSD card. Right-click anywhere in the MicroSD card folder that opens and choose "Paste" to transfer the file to the MicroSD card.
Click the "Safely Remove Hardware" icon in the system tray of the Windows toolbar at the bottom corner of your screen and choose "Eject" for the MicroSD entry.