New to Java

Hi All,
Just venturing into Java with Eclipse. Wrote a test program and wanted to get familiar with the debugger. Found that Eclipse couldn't find the JRE source to step through. After Googling about solutions like, "locate src.zip" haven't been successful. Don't see anything that looks like source in my directories.

As an aside, is them some concise reference as to exactly what the difference is among all these different marketing terms.

For example, I see some writing on the web that claims "Jave EE is the combination of the SDK, JRE and Glassfish, you can't have EE without glassfish..." Which is a statement I can't truly evaluate. My goal had been (warning noob here) to install the EE level, use Eclipse as IDE and Apache/Tomcat as the Server side parts. The former statement seems to imply, "You don't have EE if you aren't using glassfish".

Am I missing something?