In order to run the examples, we need to have the Java Compiler. You can download one from www.sun.com but this makes you more confused. I know you want to start programming now so what I can do is provide you the JDK that I used. Our Java lessons will be Java 1.4.
How to know if Java is installed properly:
In your command line... type in "java". So in your command line, it should look like this...
C:\java
If you see something about java, it should appear.