ok, in the right_column (or left column if you are using that)
FIND
Code:
<table align="center" border="0" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" class="tborder" width="90%">
It's the second line, right after the opening <'br /'>
REPLACE WITH
Code:
<table align="right" border="0" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" class="tborder" width="90%">
It gives it a shove to the right so the gap between the forumbits and navigation block is wider and the gap to the edge of the forum is matching with the left.
If you want to widen the block at all change the width setting in the above line. Don't use 100% though as that sticks it to the forumbits and looks awful!