How do I create or add a new user account?
Many Linux dostro's have a graphical tool for performing this type of administration task, Suse has yast or yast2. In the Fedora menus go too "System" > "Administration" > "Users and Groups". And I don't know much about the others.
This simple command line method should work on all Linux distributions, and probably get the job done quicker. If you are in graphical mode open a terminal window and su to root, then enter the command "useradd -m new_user_name" without the quotes, and hit enter
The -m switch tells useradd to create the user's home directory with all the needed system files in it. The above example would create the directory /home/doug. But we're not done yet, Doug needs a password to log into the system. Still as root type "passwd doug" without the quotes and hit enter, you will be prompted to enter a password for doug, and then reenter it. You may receive a message saying that the password is bad, too short or too simple but if you reenter the same thing it will probably be excepted anyway.
That's all there is to it. User Doug has been added to the system and is ready to log in. Any user can type "passwd" at the command prompt to change there own password, but only root can change the password of someone else.
Another way to add a user to the system is to type "adduser" as root and flow the onscreen prompts, you can simply hit enter for most feilds with the obvious exceptions of user name and password.
For more information on these commands try the man pages.