Put this in you postbit
Change your-domein.com to your own url
Code:
<if condition="$post[postcount] == 2">
<table cellspacing="0" cellpadding="5" border="0" width="100%">
<tr>
<td class="smallfont" style="color: #fff; font-weight: bold; text-align: center; vertical-align: middle;">Link To This Thread: <input type="text" name="link" value="http://www.your-domein.com/showthread.php?$session[sessionurl]p=$post[postid]#post$post[postid]" size="50">
</td>
</tr>
</table>
</if>
Njoy