[Gemma]

In your skin_Arcade.php find:

<tr>
                    	<td align="center" class="alt1">
                        	<a href="{$ibforums->base_url}act=Arcade">{$ibforums->lang['back_arcade']}</a>
                        	<br /><a href="{$ibforums->base_url}act=Arcade&amp;do=stats&amp;gameid={$game['gid']}">{$ibforums->lang['view_high']}</a><br />
</td>
                    </tr>
					{$extra}

Underneath that add:

<tr><td align="center" class="tcat"><b>Sponsored Link</b><br /></td>
					<tr><td align="center" class="alt1">
***YOUR AD CODE***
					</td></tr>

Put your ad code inplace of ***YOUR AD CODE***

Save skin_Arcade.php and upload