Check if checkbox is checked and show text in span
<p>I have a script that once a button is clicked it displays specified text in a span below.
How can I use this to check if a checkbox is checked and display text accordingly?<br>
I've tried so many different ways to no avail. 
<a href="http://jsfiddle.net/jamesil/w5bdX/" rel="nofollow">http://jsfiddle.net/jamesil/w5bdX/</a> 
A point in the right direction would be much appreciated!</p>
