Just follow these steps.
1.Open the Admin CP
2.Go to Look & Feel
3.Pick the skin you want to edit (This method requires you to individually edit each skin to do this)
4.Click Edit HTML
5.Select Board Index
6.Select Show Stats
7.Now copy and paste the code, should look like this.
<tr> <td class="formsubtitle" colspan="2">{ipb.lang['board_stats']}</td> </tr> <tr> <td class="row1" width="1%"><{F_STATS}></td> <td class="row2">$text<br />{ipb.lang['most_online']}</td> </tr>
Replace, {ipb.lang['board_stats']} with the title of the table. Eg. Affiliates
Replace, $text<br />{ipb.lang['most_online']} with, whatever you want to appear, like an image or text, for the main part. Use html tags for images or links.