Post customization for image and video host

I have a free image host called picmecca.com. This project involves finding the file that outputs the html in urls like the sample ones below, and adding "og:type" meta tag to the file. Similar to (<meta propert="og:type" content="article" />), to make the image as big as possible, without losing quality. The final goal of the project is to make it possible that social media (Google+ and Facebook) generate a post like [login to view URL] when users paste the pretty url onto a Google+ page or a Facebook page and click publish. The problem is that the site is currently generating posts like [login to view URL] sample urls to work with: [login to view URL] [login to view URL]