It is assumed that you know how to setup
environment variables and install software on your operating system,
for a
comprehensive guide to doing so for Windows see Configuring A Windows
Working Environment, for Unix see Configuring A Unix Working Environment
Follow these instructions to install JUnit:
Download the latest version of JUnit from
http://download.sourceforge.net/junit/
Uncompress the zip to a directory of your choice.
Add /path/to/whereyouextractedjunit/junit/junit.jar to your
Java CLASSPATH environment variable.