This package has several folders:

/src -> Java source code
/doc -> Javadoc information
/classes -> Compiled source code
/native -> C-files for JNI RRDTool support

If you are familiar with Java, you will find that Java code 
is very easy to use (no special instructions for this). 

Before you start using Rrd.java, go to the /native folder and 
follow the instructions to build your JNI shared library. 
Otherwise, you'll get nasty exceptions once you run your RRDJTool 
based application.

Hope it helps...

Sasa Markovic
sasam@dnseurope.co.uk