UNIVERSITY AT BUFFALO, THE STATE UNIVERSITY OF NEW YORK
The Department of Computer Science & Engineering

1. Download the file from this page: JES 4.3 download
2. Unzip the file to a directory in your My Documents folder.
3. Run the file called jes.bat inside the folder you just extracted.

Now JES will load, and you will be presented with the following window:

The top of this window is a program editor - it's where you can type in a program to run. The bottom is an interactive Jython session - that is, you can interact with the programming language there.