Change image from instance by clicking

Hello

How can I do to change the image of the current instance to another image that is in the library by clicking the mouse?

This is my code that in addition to playing a sound also changed the image:

###########################

var music: Boolean = true;

button_1.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler_2);

function fl_MouseClickHandler_2(event: MouseEvent): void {

var Som: som_classe = new som_classe();

if (music == false) {

     SoundMixer.stopAll();

     musica = true;

}

else {

     Som.play();

     music = false;

}

#######################################

}

Thank you

Paulo Valentim