Button render service using image?

Question

Hi BB developers I am newbie to development.I am having a problem with transparent image.I placed a transparent image on a bitmap and used that part as button render service.But when I clicked not only on the image but also on the entire screen it fires the button event. How can I make the specified image part as Button render service and remaining part not generating event.I need to place more buttons on the screen.Hope someone can help.Thanks.