How to fix in Codeignater?

Question

CodeIgniter

Hello, I am studying this product 3 versions according to the lessons for the second. Everything set up. And changed the main class in the controller:

class First extends CI_Controller {

  public function index()
  {
    echo 'Hello';
  }
}

And I launch http://site/news/index.php/first
Now, with any of my actions, it gives out:
404 Page Not Found
The page you requested was not found.

Answer 1

news/index.php/first
where does news come from?
where does index.php come from in this path?