Not what it says on the RideWithGPS instructions:
- Plug in your Garmin
- On the website, navigate to your route or ride.
- If you are a premium user, use the Garmin Write feature of the site
- Otherwise, click the Export tab then click on TCX Course
- If your computer prompts you to save the file to a specific location, place it somewhere memorable like the desktop.
- Using the Finder, My Computer or other tool on your computer, open up the drive associated with the Garmin, usually labeled Garmin
- Open the Garmin folder located inside the Garmin drive.
- Click/drag the exported file from your desktop to the NewFiles folder.
- Safely remove the Garmin (Eject on an Apple machine) and unplug it from the computer
- After powering it on click the Courses icon and locate your route
When the Garmin is turned on/disconnected form the PC, it checks the NewFiles folder and converts the file and writes it to the courses directory. It will then empty the NewFiles directory.
Make sure you only add one file at a time to 'NewFiles' before you disconnect. If you do multiple it will fail.
Also RWGPS makes you buy a premium membership to be able to get warnings on your turns, bikeroutetoaster will do it for free.
Edit: if you want to send me your gpx/tcx I can create a working Garmin course for you and send it back.