add function to one php file

The admin has 5 programs in the database, a member signsup and enters his affiliate id for only 2 of the programs. I want the script to show the 'content' for only those two programs when the member is showing his referral link. (http://www.domain.com/index.php?referid=username) This will be only one file you need to edit. I have attached a copy of the file with more description.