If you have the x-windows system working you could use the userdrake program to add users. Log in as root and run the program "mcc".
One of the modules you can add is for adding users. This is probably the easiest way. Normally a person wouldn't log into kde as root, but since you don't have a normal user yet, we'll all excuse it this time!
Note: The "mcc" program, stands for Mandrake Control Center. It is a link to the "drakconf" program. You can also select the "Mandrake Control Center" program from the KDE menu. It might be under "system".