I had a heck of a time learning how to use KNOW GOOD SAFE bike routes on Google Earth and getting them to my Garmin Unit. Finally after 6 months of working at it, and no help from Garmin Support team. I finally figured it out. It works fine, if you just remember a few minor but so so importent details. (Zoom Zoom Zoom to < then 80Ft)
Here is the link to the GOOGLE HELP PAGE WITH a MS Word document that just might help you out too.
http://sites.google.com/site/stevegsite/Home/earth-an-map-help
Download the ETrex Help Legen HCx HELP.docx Page.
This is the direct link to the Help Document.
http://sites.google.com/site/stevegsite/Home/earth-an-map-help/ETrexLegendHCxHELP.docx?attredirects=0