As the other commenter mentioned the web editor is probably the most beginner-friendly editor. It might seem a little daunting but it's actually not that difficult to edit OSM. When you save your change there's an option to request a review of it. That'll get an experienced contributor to take a look at it and help clear up any mistakes.

OSM also has a public database of GPS tracks that contributors use to aid in mapping. Even just walking the trails with GPS tracking on and then uploading the tracks to OSM without doing anything else is a valuable contribution that will allow other contributors to map the trails at some point in the future.