*thinks*
Actually, I believe you can just use a text document and the command prompt to run Java.
To be honest though, I have no idea how to set that up. My professor uses the whole text document/command prompt thing, but I personally think it's easier to just download JCreator like Soujiro said. It helps out a bunch when it comes down to actually compiling it (it sometimes gives useful suggestions to fix the problems), typing the code in (JCreator puts different things in different colored fonts, making it easier to read), and organization (lists methods and objects in an organized matter so you don't have to search through your code for any of that).
If you're really determined to use the whole notepad/command thing though, I can see about getting the information for you.