How do I upload a file to my GPS (garmin c340)? I purchased a preloaded garmin c340, and now I have a file I downloaded off the web (gpx file), with all the red light cameras and such, and a different splash screen as well, but my gps did not come with MapSource, the software that is used for that because it says it doesn’t need it since it is preloaded. I tried to download it from Garmin, but they only relese the “upgrade”, so it does not work. Does …