Controller - newbie bug help

[eluser]axecutioner[/eluser]
Hi everyone! I'm brand new to using CI and also PHP frameworks in general. I have followed all of the instructions in the General Documents section, up to the Controllers section, because this is where I got stuck.

I'm following the Blog example that the help indicates. The file name is "blog.php" with lowercase b, the code copied directly from the help page, and the file rests in "system/application/controllers/". Instead of saying "hello world" as I expect, I get this:

"No input file specified."

My URL is the following: http://www.firefalcon.net/index.php/blog/index/

I have extracted the "system" folder and "index.php" to the root of my site. In "system/application/config/controller.php" I set this line:

$config['base_url'] = "http://www.firefalcon.net/";

What more do I have to do to get on track?

Any help for a newbie is much appreciated