...Longinus had to ask how to start X....I don't think you can just tell them to go and edit a file....
Also, just incase you get a ton of search results, and with keywords such as that you should, all you need to do is click on the kde button in the bottom left corner and then settings>Control Center(or something like that)>Administrative options>Then hopefully you can find it inside of there under login or something to that effect. Sorry that I can't be very in-depth, I'm on a windows box at work.
Also, some basic newbie tips:
You're running as root right? Don't, I know there isn't that much of a risk to most users if they run under root but it is rather nice to have your own name and your own EVERYTHING if you have more then one user, and it will protect you from almost every linux virus there is, as few as there are.
To make a new user:
Click KDE button>system>User *something or rather*> in the dialog click add user and then Enter your information.
You will want to use that site if you are just a user because it will make your desktop so much nicer.
If you ever need help feel free to IM me at:
(once I get aMSN installed once again)
As you can tell, I change my name a lot
Good luck with your learnins