If you want just to add a waypoint symbol in your nuvi, here it is :
In Nuvi, you can easily add these references points, to help you remember your favorite locations. Once added to the GPS device, you can quickly get directions to and from the custom waypoint.
1. Turn on your Garmin Nuvi.
2. Navigate to the location you would like to save as a waypoint.
3. Press the "Where To" option from the main screen and press "My Locations."
4.Touch "My Current Location." Your location will be saved as a POI (Point Of Interest) and indicated on the map with an arrow.
5. Press "Save" on the bottom right side of the screen to save the custom POI.