Unix is a multi-user operating system. Thus, before you begin, you must login to authenticate yourself as an authorized user. On a Truman computer, your username is your TRUMAN domain network ID, and your password is your TRUMAN domain network password. On your own system, you may choose your username and password to be whatever you wish.
You may login using a completely text environment. This is common when connecting to a remote machine using a program like telnet or ssh. As soon as you authenticate, you are presented with a shell and can type commands.
You may also login to a graphical environment. This is common when sitting at a physical workstation. A graphical login prompt is presented which leads to a full graphical environment after you have authenticated. In this case, it is necessary to open a ``shell window,'' to type commands, and you'll generally find options to do that under a menu.. Sometimes a shell window is referred to as an xterm or rxvt window after the names of popular programs that provide a graphical means of running a shell.