POTD question

[Webcutie]

I am trying to set up a POTD, Tried tons of scripts and finally got one to work.... it's very simple...
It's from here: tomsnewbiebooster.com/resources/picture-of-the-day/script.html

The question that I have is..... How do I make multiple thumbnails from that POTD for an affiliate program? I noticed a lot of people have it off of an php file.... like potd/thumbnails.php?size=88x88 or potd.php?site=sitename&type=thumb1 How do you do this exactly? Someone please help me or direct me to the right place!... Thanks a bunch!!