Loading movieclips from library

hi.

i used this code with linkage to load a movieclip from library using flash action script 3

btn.addEventListener(MouseEvent.MOUSE_UP,goLayersSite);

function goLayersSite(Event)
{

var myMovieClip:MovieClip = new Tree();
empty.addChild(myMovieClip);
}

i want to know how am i able to load a flash movie clip from my current library into my stage with using a button via flash action script 2.

since im using other codes in action script 2 i can not cancel them and i really need to load a movie clip in my AS2 FLA.

please help me.

thanks:trout: