This question's been asked and answered a lot of times. So, since you're new to the Forum, let me give you a tip: Clicking on the Search button up there. Well, the normal Search (top choice) is not really very good for some things. For instance, if you put in "root" or "login" you'll have 20 pages, probably not many of which will even address your problem. The SECOND Search box (Google-Fedora) will give you a lot more info. Maybe "root login" would be a good place to start.
Alternatively, you can certainly select the Advanced Search feature for our normal Search engine and select the Guides & Solutions Forum and browse for the topic, which is also covered there.
Basically, the devs don't want new users to destroy their systems by making errors in a gui root environment, so they've made it a bit more difficult. Most of us never, never need to go into the gui root environment and just use a terminal and "su -" to handle things.
Edit: Well, now that I've given you some tips, how about an answer???? Okay: http://forums.fedoraforum.org/showthread.php?t=227169