You didnt tell me this was for 3.6
To upgrade, You just have to update the hacks. Most hacks either were updated for 3.8x or already work with 3.8.
Ok - try this:
In postbit template replace
PHP Code:
<!-- message -->
<div id="post_message_$post[postid]">$post[message]</div>
<!-- / message -->
with
PHP Code:
<!-- message -->
<if condition="(($post[postcount] % $vboptions[maxposts] == 1)) and ($show['guest'])">
<span style="margin: 2px; float: right; width: 301px; height: 251px;">
ADSENSE CODE HERE
</span>
</if>
<div id="post_message_$post[postid]">$post[message]</div>
<!-- / message -->
you will have to replace ADSENSE CODE HERE with the actual code.
The code is for 300 * 250 Medium Rectangle Format,Edit width & height parameters if you want to use any other format.
Ad is shown on the first and last post (modify if you want)
Ad is shown to guests Only ( remove "and ($show['guest'])" to show to all)