Custom Shortcode Creator

Hello, I try ti use Custom Shortcode Creator (from Crawled Content) from démo but I don't find how to make it works. I wanna extract data from head. shortcode_20minutes_published_time => //meta[@property='article:published_time']/@content I check this with google > [class/id/xpath/regex] @@ [class/id/xpath/regex expression] but I don't find what library or script using it. Can you try to explain to me how to do ? Thx ! ! ! ! ! !