Which template is this one on the picture?

[GameWizard]

Well the template is not a problem, it's located in template FORUMDISPLAY and the code you're look for is this:

<td class="tcat" width="100%">$vbphrase[threads_in_forum]<span class="normal"> : $foruminfo[title]</span></td>

As for adding images, I would say you need something like this:

<if condition="$forum[forumid] == X">Image Code Here</if>

Where X is ofcourse the ID of the forum, and the Image code fits in there, depending on what you want to show. And just plug in that code before the "$vbphrase[threads_in_forum]" in the original code, or wherever suits it best. The code above needs to be copied as many times as needed for as many forums as you'd like to show an icon for.