This post will be a little more basic than most things I write here. I'm used to using MacOS/X on the desktop and Linux on the server side. So when I have to use Windows for one reason or another it sometimes takes me a bit to figure things out.
Today I was helping a co-worker with Oracle Application Express (APEX for short) and the install directions said to run "cd $ORACLE_HOME/apex" and then run some commands. The cd command didn't work because Windows does environment variables different than Unix operating systems.
This article covers it in more detail but in short Windows indicates environment variables by putting a % (percent sign) before and after the variable. Variables are not case sensitive.
You can show them by running "echo %ENV_NAME%" and set them on the command line by running "ENV_NAME = new_value". You can make the setting part of your login profile by right-clicking on "My Computer", then click Properties, then Advanced, and then Environment Variables. This is for XP, the location may be different on Vista or other versions of Windows.