Please note that official support for this menu version has now ceased. There are still plenty of users, though, and the forum is still running. Some of our long-time users may be able to help you out.
By "add sound," I assume that you want a sound to play when you mouse over a menu item (rather than playing a tune as the result of selecting a menu item???). If that's what you want, then the Activating Functions example should get you started; that's exactly what it does, to demonstrate the use of the onfunction and offfunction properties.