OOP:Adding Movie clip from library

Hello guys
I’ve got an instance in the library linkaged to Classes.Lights.as
At the Lights.as I have got

light.graphics.beginFill(lightColor);
light.graphics.drawCircle(0, 0, lightSize / 2);
light.graphics.endFill();

addChild(light);

for some reason I’d like to change it to the light from my library.
I’ve tried

private var light:MovieClip = new MovieClip();

but that doesn’t work.

How can I do it in OOP?