How to download from a GPS

1. Oregon Series Owner's Manual page 38 (page 44 of the pdf file).
2. After copying the files named .gpx to your computer follow the upload-howto.
3. For adding the ways (paths) itself to the OpenStreetMap you should follow this guide.

There are a couple of possible answers to this question - what follows is probably the simplest** and most generally applicable way if you've never connected your GPS to a PC before. There's a bit of guesswork involved (I don't have a Garmin Oregon, but a couple of different ones).

You'll need a USB cable. It looks like Oregon uses a standard "mini USB" cable - (a) one probably came with your GPS and (b) even if not you've probably got lots of them around.

On a Garmin eTrex, you'd probably have a setup option called "Interface" and within there be able to select "USB Mass Storage" mode. On a Garmin Nuvi (and I'd expect on an Oregon) you don't have to do that - it should appear as a removable disk on your PC (after a short delay).

As an example, on my (Windows 7 64-bit) PC my eTrex appears as "Removable Disk (D:)" and my Nuvi as "Garmin nuvi (D:)".

If I open that drive for the eTrex I see a series of files ending in ".gpx". There's one of these created per day. You can upload from there directly to OSM.

If I open that drive for the Nuvi, I've got a "D:GarminGPX" folder. In there is a "Current.gpx" (which is today's) and a folder called "Archive", which contains number ".gpx" files, one per day, that can be uploaded to OSM.

**other options which may or may not work for you involve installing the software that came with the GPS and using that to fetch GPX traces from the device, or using software such as GPSBabel to fetch them.