[flexcoders] creating a class - question extending

[luvfotography]

Hi, I'm trying to create a class that extends the image class, 
I need to associate a username with the image,
Here is what I have:

package 
{
        import mx.controls.Image;

        public class imageWithData extends Image {
                private var _username:String;
                
                public function imageWithData() {
                        super();
                //      _username = ??? 
                }
                public function set username(value:String):void {
                        _username = value;
                }
                public function get username():String {
                        return _username;
                }
        }
}

I am unclear as to what goes after the 'super()'
do I need a _username = something?

thanks,