Click image to load another


I am trying to create sort of a walk through of a mobile app. What i need is something to display a picture to start off with, then click certain coordinates which would be the buttons and it load another image to replace the original. Can anyone throw together just a basic code? here is what i have so far

<map name="map1">
 <area href=".\pics\test3.png" shape="rect" coords="103,224,169,242" >
 <area href=".\pics\test2.png" shape="rect" coords="30,92,56,116">