Johncms Forum Posts thumbnail preview on homepage

Please i urgently need the codings on how to upload a thumbnail (image preview) to forum posts that will show on homepages beside the post topic. Just like the one in the image below..... I have tried different methods but i cant get it.

Everyone should mod it. Because The Latest
Version Pretty Awesome than the older versions.
So Pls Keep Try To Mod The Johncms 7.

its my site script check out http://ezesell.cf

They used javascripts.

Ok thank