Certain Garmin GPS models come with SD cards that you can remove in order to add or update maps. Once you've removed the SD card from your Garmin, you can also copy its contents onto another SD card in order to create a backup for yourself or share maps between Garmin GPS units. The process is the same as that used for copying any files between drives and removable devices in the Windows operating system.
Slide your Garmin's SD card into your SD card reader.
Click the Windows Start button and select "Computer" to open an Explorer file browser window. Double-click on the SD card icon to display its contents.
Use your mouse to highlight all of the files you want to copy, then press "Ctrl-C" to copy them.
Create a new folder on your desktop by right-clicking and selecting "New" and then "Folder." Name the folder whatever you want, then open it and press "Ctrl-V" to paste in all of the Garmin SD card's files.
Remove your Garmin SD card from the SD card reader.
Insert the new SD card into the SD card reader.
Double-click the folder you created on your desktop to open it.
Highlight all of the files, then press "Ctrl-C" to copy them.
Double-click on the new SD card icon in the Explorer window.
Press "Ctrl-V" in the SD card's pane to paste the files onto the new SD card.