i am trying to run the javac command from the command prompt. However I am being reported the following message: 'javac' is not recognised as an internal or external command...
Does anybody know what I need to do? is it something to do with the class path?
No, it has nothing to do with classpath. It has to do with PATH. You need to put the directory that contains javac.exe in your PATH. In Windows this is usually done with the Environment Variables button on the Advanced tab of the System control panel. (At least on XP. 98 uses AutoExec.bat or somedamnthing, and NT has a similar control panel setting, but in a different place.)
PATH is what Windows (or the command shell) uses to find the program whose name matches the first word of the command you type.
So when you type
javac something something
the command shell searches through all the elements in PATH to find javac.exe or javac.bat. This has been around for a long time and has nothing to do with Java. Unix also uses a PATH environment variable for the same purpose.
CLASSPATH is what the JVM uses to find classes.
You can set a CLASSPATH environment variable, but a lot of people (myself included) don't consider that a good idea.
Better to just use the -cp or -classpath command line option to java or javac.
The problems with using CLASSPATH are
1) Not all apps need the same classpath.
2) Some programs ignore it and use their own environment variables or config options.