Setting environment variable PATH on Windows 7

Windows 7

1. Select Computer from the Start menu
2. Choose System Properties from the context menu
3. Click Advanced system settings > Advanced tab
4. Click on Environment Variables, under System Variables, find PATH, and click on it.
5. In the Edit windows, modify PATH by adding the location of the class to the value for PATH. If you do not have the item PATH, you may select to add a new variable and add PATH as the name and the location of the class as the value.
6. Reopen Command prompt window, and run your java code.

http://www.java.com/en/download/help/path.xml