The message is stating that there is no Open Graph image set for your home page, so Facebook is automatically choosing an image as best it can.
The best way to fix is to go to the Open Graph -> Configuration area and in the Defaults box, add the following line:
image=http://www.elmarada.org/link-to-your-logo.jpg
Update that link to a good, generic image on your site, like a logo. Then, that image will be used on all pages of your site that doesn't have an image explicitly set, like your home page.
I hope that helps, but if not, let me know.
Thanks,
Alex