Mac OS X has a Java Virtual Machine (JVM) already installed, so all you need to do is install Jython.

1. Move the Jython-21.class file from CD to your desktop or a folder on your computer.
    
2. Open the Terminal.
    
3. Change directories to the Jython directory that contains the Jython-21.class file.
    
4. Type:
   

   Java -classpath . Jython-21

   It will ask you if the command is OK; type:
   

   y

5. The Jython install wizard will launch. See the troubleshooting section if you encounter problems.