Stage in Static Function

Hello there, and thanks in advance 4 ur valuable time!
I am new to OOP, so things are still a little blurry for me.
I 've been trying to access the stage (& the parent also) through a public static function inside a public class (the document’s class) which extnds MovieClip but I get an error “1120: Access of undefined property stage.”
What do I do wrong?