Linux server admin - Adding user accounts, resetting passwords

When logged in as your own account and changing your own password:

$ passwd

As superuser (or root), changing the password for other accounts

Find out list of users

$ cat /etc/passwd | cut -d: -f1

Change password for account "guest1"

$ passwd guest1

Add users (with default configuration)
$ useradd guest1
(http://www.thegeekstuff.com/2009/06/useradd-adduser-newuser-how-to-create-linux-users/)