Once you've completed your mapping, you need to get the information off your receiver and into the right format. The simplest ways of getting traces off your GPS are using a direct cable connection or a removable memory card. Some recent receivers can act as USB mass storage devices, allowing you to get your traces onto your PC with a simple file copy. For older units, you may have to use the software that came with your GPS.
OpenStreetMap only accepts traces in GPS Exchange format (GPX)—an XML vocabulary for traces and waypoints. You can find out more about the GPX vocabulary at http://www.topografix.com/gpx.asp. OpenStreetMap also only accepts GPX files with timestamps on each trackpoint in the trace. This is to prevent mappers from uploading traces that have been converted from an existing map database, which will usually be subject to copyright and will therefore, not be suitable for use in OpenStreetMap. This doesn't present a problem most of...