Do I need to load My_ classes manually?

[eluser]sahanlak[/eluser]
I have a class named "My_admin" which extends the controller class, and its inside the library folder. I then extend this "My_admin" class and create other classes which are for an admin area. Anyway I couldn't get that far because I can't extend the "My_admin" class in other controllers. It throws an error saying..

Code:

Fatal error: Class 'My_admin' not found........

Do I need to load "My_admin" manually? I'm using a linux server and how should I named my classes? I'm asking this because when I migrate the application from windows to linux I got some file naming issues.

Thank you