How to call the movieclip of a class that has base class

1

So here is my problem I’m having almost 2 days now. I searched from forums to forums and other sites and still no luck.
Imagine a movieclip “green ball” in the stage which has its own class “GreenBall” and a base class of “Ball”.
Therefore :

public class GreenBall extends Ball

There’s a function in “Ball” that needs MovieClip type to work. Ex:

this.hitTestObject(MovieClip)

Now my question is how to pass the “green ball” movieclip to the said function.
Note: green ball doesn’t have instance name because I may create it both static (on stage) and dynamic (on AS3).
It sounds easy for others. But I’m just a beginner in AS3 and programming. Thanks!