Path tells the OS where to look for executables. So if you want to open a command window to any directory and say "Java -version" you need the path to include the jre\bin directory.
Classpath tells the JVM where to look for classes. When I use classes in the JUnit.jar I have to make sure the classpath includes the JUnit.jar.
You can set either or both in the Control Panel - Start / Settings / Control Panel / System / Advanced Tab / Enviroinment Variables button.
For my own little Java programs I often make bat files to start them up. Then I can modify path & classpath right before running the program. You can override classpath iwth the -cp switch on the Java command.
Try some simple programs to see how this works ... holler again if that's not enough detail. Cheers!
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi