Start from home
In the UNIX world you need two things just to be able to get annoyed: a username and password. The system administrator (sysadmin: Chris Watson) assigns you a username but you get to pick your password. Please make your password something you can remember but hard for someone else to guess, preferably with a couple non-alpha characters like *, &, $. Alternatively you could use your username as your password, unceremoniously lose your account and all or data, incur the wrath of your colleagues, and maybe have the FBI knocking on your door. If you forget your password, there is no getting it back, but you can be given a new one by the sysadmin.
When you log in you will be in your "home" directory. You may have many places you haunt and homes away from home, but this is where you start. If you forget where you are, using the cd command with no arguments gets you home (please, the Dorothy jokes are old). You can also type cd ~ and get there too. Most CERI computers are networked so you're home is the same no matter what computer you log into. This is accomplished by a very nerdy thing called NIS and your home physically exists behind locked doors. The down-side is, if the server behind this locked door goes down, get out the pencil `cause you ain't usin' the computer. There are some rogues on the CERI domain (internetspeak for our part of the world) that are not using NIS. If you're not sure whether you have an account (a username and password) on one of these rogues, then you don't so just leave it alone.