A screenshot or a link to your forum would better help explain the situation.
The footer width is set to be the same as the header and everything else, it's probably not a simple change to make the edit you are requesting. (Nor a good idea)
If you really wanted to change the footer width you would edit the
footer template.
Find the line:
Code:
<div id="footer" class="floatcontainer footer">
And add a custom width, it should override the value specified in the class:
Code:
<div id="footer" class="floatcontainer footer" style="width:1000px;">
Where 1000 is the width in pixels- change it to whatever you want.
But again I caution you this is probably going to make things worse, not better.
(You can of course always undo it.)