The code you want really depends on whether you want to click a button and have a ball bounce or use the mouse to drag a object against a wall.
Id recommend this website that shows a very simple tutorial on collision detection.
http://flash-creations.com/notes/astb_bounceCollide.php
you could however skip code entirely and use motion tweening to create the same effect. If you were making a video rather than an interactive website or game.
