Command Prompt

Hi all I am new to this site greetings.

I have a query about HelloWorld basic startup in Java

I have saved the code in a notepad file in my C drive and am trying to open it in command prompt.

I open cmd and C:\Users\(my admin name)> appears

I then enter either of these /> javac HelloWorld.java
/> java HelloWorld

but the cmd prompt doesn't associate it with my saved notepad file HelloWorld.java

any ideas help would be appreciated, nice idea for a site by the way I'm impressed, and looking around for things to play with on the web.