I'll admit it at the outset: I'm in a bad mood today.
But when I see things like this, and this, and this, all talking about running courses in Facebook, I can't help myself
(Okay, really I can. But in this case, I don't want to).
Read Facebook's terms of service.
The "User Content Posted on the Site" section is particularly relevant here:
When you post User Content to the Site, you authorize and direct us to make such copies thereof as we deem necessary in order to facilitate the posting and storage of the User Content on the Site. By posting User Content to any part of the Site, you automatically grant, and you represent and warrant that you have the right to grant, to the Company an irrevocable, perpetual,...