Hi in addition to stf 's remarks, take a look here to get some hints, http://wiki.openstreetmap.org/wiki/Using_OpenStreetMap I would go for JOSM since it allows you to select (double click) a gpx file with points or a trace (current at Garmin) and gives a suggestion about the area for a download. And yes you’ll have to install JOSM or use Potlach2 or ID (quit friendly for a mobile) instead without a download. Enjoy. PS try to select those roads that are n't on the OSM map or incorrect.

Hi in addition to stf 's remarks, take a look here to get some hints, http://wiki.openstreetmap.org/wiki/Using_OpenStreetMap I would go for JOSM since it allows you to select (double click) a gpx file with points or a trace (current at Garmin) and gives a suggestion about the area for a download. And yes you’ll have to install JOSM or use Potlach2 or ID (quit friendly for a mobile) instead without a download. Enjoy.