Name button instances

You'll provide instance names for the buttons on the Stage so that you can refer to the instance names in ActionScript.

1.	On the lower-right side of the Stage, select the button at the left. In the Property inspector (Window > Properties > Properties), type goScene_btn in the Instance Name text box to name the instance of the symbol.
2.	Select the middle button and use the Property inspector to give the button an instance name of attachMovie_btn.
3.	Select the far-right button and use the Property inspector to give the button an instance name of playSound_btn.