Are you talking about <http://jid3.blinkenlights.org/>?

If so, I just downloaded their tar.gz.  They seem to be distributing a
NetBeans project (not the best way to distribute code).

The good news is that NB projects have a dist/ folder, in which one can find
the JID3.jar (another violation of convention - JAR files are usually named in
lower-case) and a javadoc/ directory.

Extract the JID3.jar and put it in your project's class path.  This is the
same for any Java library distributed as a JAR - you put the JAR in your
project's class path.

http://java.sun.com has some excellent tutorials, many of which deal with
class paths and JAR files.