You'll need to remove "public_html" so the code you should be using is (don't change the $forumid below):
Code:
<tbody>
<tr>
<td class="tcat" style="background:#000000 url(/forums/images/Files/$forumid.gif) no-repeat top left" colspan="<if condition="$vboptions[showmoderatorcolumn]">6<else />5</if>">
You can also remove "#000000" in the code. It's not necessary for it to work.
*
IMPORTANT: For it to work properly
do not change "$forumid.gif" in the above code. Only the image name will be changed. In your case since you're using Forum ID 1 name the image file to "1.gif". Again, not the code.