This is my previous thread...
http://wordpress.org/support/topic.php?id=26978
Thank you, the posts were getting too long and my topic has basically changed! :p
To sum it up, I am trying to find out what file I need to edit and what php I use for version 1.2.1, so that I can have specific ads show up on specific categories. The two nice men who helped me had given me instructions on how to do this for wordrpress version 1.5 only. (My cpanel does not upload to the latest version, and it's much easier using my cpanel considering I have to do hundreds of blogs, so I can't upgrade to 1.5 unless I manually download all of the blogs myself.)
Another thing I did not post up on my previous thread is even if I can make it so each category shows a specific ad, how do I make it so that the index.php file (which shows all recent blogs of all categories) shows yet another ad code? Without the ad shown on the main index page showing up on the specific category pages? I also don't want an ad that matches the category of the last post to show up on the main index, I only want that specific ad to show up on that category's page.
Hope that makes sense. :) This is important because I am also running an ad exchange site and I have to put up my member's ads to category-specific pages (they choose their category they want their ads to be displayed) so their impressions are used up on relevant viewers of their ads, which means more potential visitors for them.
So you can see my predicament. :)