How do relationships work in Views?
If you add a relationship in the View definition (Third column of the view input form), and select the Content:author from the dialog, you have created a link in the view that exposes data regarding the author. This will give you access to more fields that can be displayed in your view.  

Check out the video series, "Taming the Beast" at nodeone.se to get a better understanding of what Views can do.