Edit
http://www.al-birmingham.co.uk/themes/igames/theme.php (using a plain-text editor), find
// HTML template for template sub_menu
// special note: I left the JavaScript 'hide' off of the first and third buttons to help avoid trouble keeping sys_menu open. :Donnoman
if ($CONFIG['custom_lnk_url'] != '') {
$template_sub_menu = <<<EOT
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr>
<!-- BEGIN custom_link -->
<td class="top_menu_left_bttn">
<a href="{CUSTOM_LNK_TGT}" title="{CUSTOM_LNK_TITLE}">{CUSTOM_LNK_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<!-- END custom_link -->
<td class="top_menu_bttn">
<a href="{ALB_LIST_TGT}" title="{ALB_LIST_TITLE}">{ALB_LIST_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="javascript:;" onmouseover="MM_showHideLayers('SYS_MENU','','show')">@</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{LASTUP_TGT}" title="{LASTUP_LNK}">{LASTUP_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{LASTCOM_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{LASTCOM_LNK}">{LASTCOM_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{TOPN_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{TOPN_LNK}">{TOPN_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{TOPRATED_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{TOPRATED_LNK}">{TOPRATED_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{FAV_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{FAV_LNK}">{FAV_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_right_bttn">
<a href="{SEARCH_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{SEARCH_LNK}">{SEARCH_LNK}</a>
</td>
<td width="100%"> </td>
</tr>
</table>
EOT;
} else {
$template_sub_menu = <<<EOT
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr>
<!-- BEGIN custom_link -->
<!-- END custom_link -->
<td class="top_menu_left_bttn">
<a href="{ALB_LIST_TGT}" title="{ALB_LIST_TITLE}">{ALB_LIST_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="javascript:;" onmouseover="MM_showHideLayers('SYS_MENU','','show')">@</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{LASTUP_TGT}" title="{LASTUP_LNK}">{LASTUP_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{LASTCOM_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{LASTCOM_LNK}">{LASTCOM_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{TOPN_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{TOPN_LNK}">{TOPN_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{TOPRATED_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{TOPRATED_LNK}">{TOPRATED_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_bttn">
<a href="{FAV_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{FAV_LNK}">{FAV_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<td class="top_menu_right_bttn">
<a href="{SEARCH_TGT}" onmouseover="MM_showHideLayers('SYS_MENU','','hide')" title="{SEARCH_LNK}">{SEARCH_LNK}</a>
</td>
<td width="100%"> </td>
</tr>
</table>
EOT;
}
and add the code that Phil suggested. This is plain HTML, as I suggested. I will give you an example: If you want to add a link to Google, find
<!-- BEGIN custom_link -->
<td class="top_menu_left_bttn">
<a href="{CUSTOM_LNK_TGT}" title="{CUSTOM_LNK_TITLE}">{CUSTOM_LNK_LNK}</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
<!-- END custom_link -->
and add before it (in a new line)
<td class="top_menu_left_bttn">
<a href="http://google.com/" title="Let's go to Google">Google</a>
</td>
<td><img src="themes/igames/images/menu_spacer.gif" width="2" height="35" border="0" alt="" /><br /></td>
As there is a conditional at athe very top that checks if a custom link exists or not, you'll have to perform another edit: find
<!-- BEGIN custom_link -->
<!-- END custom_link -->
and add the code I suggested above in a new line before it as well.
Doesn't get simpler than that.