OK, IT WORKED!! So, if anyone reads this and is using a MacBook Pro here's the scoop:
Command + Shift + 4 will make your cursor a crosshair. Whatever you select (in this case your treasury) will be saved as a 'screenshot' on your desktop. We'll call it 'File Awesome'.
On your fb fan page, Add a Photo but actually select 'File Awesome', which is saved on your desktop.
In the description put a blurb about the treasury, if you like, and the link back to Etsy.
Voila!! Treasury posted to facebook!!