I have installed shortcode and it's working fine for post. I have used for floating also. When it post to facebook it shows post-image in window. I want my website logo to be appeared there. Let me know how to do that.

I have installed this plugin and icon is displaying on website. But when I click on facebook or any other icon it is not displaying my facebook fanpage description. In pop-up it's showing blank box having no description. What I have to do?