I'm going to move this to the Unix / Linux forum, since this is only tangentially related to the
SCJD assignment.
Are you working on the physical Unix machine? That is, can you confirm that you are not telnetting in, or otherwise connecting remotely?
Are you running a graphical user interface on the Unix system? Under Unix this should be the X11 Window System (often called X11 or X). Many Unix and (most) Linux systems have a desktop environment running on top of the X11 Window System - typically Gnome or KDE. Are any of these sounding familiar?
If the answers to both questions are yes (yes - you are running on the physical Unix system; and yes - you are running a graphical user interface), then you may be able to enter into your xTerm the command "
export DISPLAY=:0.0" (without the quotes).
If you are not physically attached to the Unix system, then you will need to provide a little more information before we can provide any more help.
If you are not running a graphical user interface on the Unix system, then there are ways around it, but they may be more trouble than they are worth.
Finally - for the SCJD project, you don't really need to
test under Unix systems (although I applaud you for trying). One option you might want to consider is getting a live CD so you can run Linux on your own personal computer without actually installing Linux. You could then use this for testing.
Regards, Andrew