Ok- Lots of people are arriving here by doing a search on how to post a fan photo on Facebook. So I'll tell you! Because it wasn't obvious to me at first either:)
On the page that you want to post a photo - just under the comment box there is a grey box that says "Attach" and it has icons for a link, photo, an event or a video. Click the 2nd icon to attach a photo and it'll take you through the process to post it.
And while you're at it - become of Loopy 4 Ewe Fan at http://www.facebook.com/loopy4ewe and I always love to see those fan photos!
If this helped you - leave a comment to let me know and say hey.