I can't find class_php to fix my errors

My website is hosted on a subdomain, so I tried to fix errors in my script by using this and this. I can't find the class_php file, and the class_pagination.php doesn't have www in it. I'm running php 5.6


Actually I found www in class_mysidia.php or whatever it's called. But I think I realized the problem, my site isn't subdomain.domain.com, it's domain.subdomain.org. What do I need to change the format to in this case? And do I just need to edit the class_mysidia.php file