^ well, I can clearly see the logo source code in header template ...
admin panel --> templates --> click on current theme's template set --> header templates --> header
Ok I know Im being a noob but what do I change
<div id="container">
<a name="top" id="top"></a>
<div id="header">
<div class="logo"><a href="{$mybb->settings['bburl']}/index.php"><img src="{$theme['logo']}" alt="{$mybb->settings['bbname']}" title="{$mybb->settings['bbname']}" /></a></div>
<div class="menu">
<ul>
<li><a href="{$mybb->settings['bburl']}/search.php"><img src="{$theme['imgdir']}/toplinks/search.gif" alt="" title="" />{$lang->toplinks_search}</a></li>
<li><a href="{$mybb->settings['bburl']}/memberlist.php"><img src="{$theme['imgdir']}/toplinks/memberlist.gif" alt="" title="" />{$lang->toplinks_memberlist}</a></li>
<li><a href="{$mybb->settings['bburl']}/calendar.php"><img src="{$theme['imgdir']}/toplinks/calendar.gif" alt="" title="" />{$lang->toplinks_calendar}</a></li>
<li><a href="{$mybb->settings['bburl']}/misc.php?action=help"><img src="{$theme['imgdir']}/toplinks/help.gif" alt="" title="" />{$lang->toplinks_help}</a></li>
</ul>
</div>
<hr class="hidden" />
<div id="panel">
{$welcomeblock}
</div>
</div>
<hr class="hidden" />
<br class="clear" />
<div id="content">
{$pm_notice}
{$bannedwarning}
{$bbclosedwarning}
{$unreadreports}
{$pending_joinrequests}
<navigation>
<br />
^ admin panel --> Themes (at Quick access menu) --> click on the active theme -->
scroll down to see Edit Theme Properties
for Board Logo , enter your logo path eg. images/logo.png & save theme properties
thanks so much for your help ranjani