Adding JFreeChart source to my project

Hi, hopefully this is an easy question. (But not for me.)

I'm having some problems with JFreeChart, and I'd like to be able to add a few print statements to the JFreeChart code so I can tell what's going on. How can I add the JFreeChart source code into my project so that if I edit some of the JFreeChart source, that gets detected and compiled into my application? Thanks.