As this software has been created using the java language (wikipedia link), in order to successfully run it, you will need to have a Java Virtual Machine installed, 1.4.0+ compliant. (check) Being archived as *.jar, the software can either be tested with Java Web Start (wikipedia link), as an applet (wikipedia link), or as a classic stand-alone application (by double-clicking or by typing java -jar myJarFileName in your shell).
If you want to look at the source codes, they can either be found in the latest release and in the SVN repository (browse using ViewVC).