you need a class Tile with PImage x y addX addY and then look at the bounce examples in the learning section http://processing.org/learning/topics/bounce.html

even look at Basics | arraylist objects: http://processing.org/learning/basics/arrayobjects.html

It is not the array list that bounces, it is its content... The list is an abstract object, but the objects it holds can be displayed and moved.
As said, you have to wrap the images in a class holding the coordinates and direction of the image, and iterate on the list to move and display each element.

Link

http://processing.org/learning/basics/arrayobjects.html