Thats not what they are saying
For example if you are creating a page about the movie 'The Rock' you would include this meta data:
* <meta property="og:title" content="The Rock"/>
* <meta property="og:site_name" content="IMDb"/>
* <meta property="og:image" content="http://ia.media-imdb.com/rock.jpg"/>
They seem to want to know the exact image url.
As far as a script link you might need to actually read more into that mod for facebook
Your free to discuss code mods outside product support in the mod corner.
Maybe the variable you want to use is $imgdisp thats a link to the image surrounded by a link to the script page