createEmptyMovieClip in class

programming flash
1

How do I create MovieClip in class. I tried to use createEmptyMovieClip. But unless I use _root.createEmptyMovieClip, it is not working.

class LoadM {

    private var mcAlpha:Number;
    var defX:Number;
    public function LoadM() {
        var picLoader_mc:MovieClip;
        _root.createEmptyMovieClip("picLoader_mc",1);
        _root.picLoader_mc.loadMovie("picture.jpg");
        trace(mcAlpha);
    }
    function get trans():Number {

        return mcAlpha;

    }
    function set trans(transpancy:Number):Void {

        mcAlpha = transpancy;
        _root.picLoader_mc._alpha = mcAlpha;

    }
    public function defineX(deX:Number) {
        defX = deX;
        _root.picLoader_mc._x = defX;
        trace("something");
    }

}

This code is working fine. But I don’t want to use _root.createEmptyMovieClip. I tried this.createEmptyMovieClip, but it is not working.