Aurelien,
I'm not sure if you'll like my suggestion, but perhaps some form of the lessons / advice you give could be posted online?
I presume your lessons will include practical listening experience, which will be harder to convey on a html page, but never the less this could be solved by providing a download of the needed "materials" for the lesson, or even stream the audio to the web page.
I can volunteer to re-write parts of the material / re-read things etc if your open to posting the lessons online?
Cheers, -Harry