If you want a static sidebar (in which you simply edit the HTML) you edit your header and footer inserts.
You put the whole forum inside a table.
Example, for a left sidebar, in your header you put something like...
<br /><table width="100" border="0"><br /><tr><br /><td width="20%" valign="top"><br /><br /><!--Put HTML for Sidebar Here--><br /><br /></td><br /><td valign="top"><br />
Then in the footer, close out the table.
[code]
</td>
</tr>
</table>
[code]
If you want a "smart" sidebar, like here with info about the forum, then you need IIP.