You can download the JDK
here, There are links for both the JDK and JRE there. So be sure to use the JDK one.
Once installed, you need to add the JDK's bin directory to your path. (you may have already installed the JDK and are just missing this setting.) You can read how to do such
here. You can also search this forum since how to add the JDK to your path is a common question.
[ August 06, 2008: Message edited by: Mark Vedder ]