One way to create new windows is to type xterm & in a window. (The & allows one to keep both windows active instead of freezing the window in which the command was typed until the xterm process is killed.)
Another way to create a new window is more specific to this system. First move the mouse to the dark gray, background area and press the right mouse button. A menu should appear with a selection of possible computers from which to open a window. While you keep the button down, move the mouse down until the type of window you wish to create is highlighted. Local places a window local to the computer you are using. There are also options available for opening a window logged in to duncan, cranberry (for CM-5 work), and pulsar (for MASPAR work).
When the ``ghost" outline of the window appears on the screen, use the mouse to move it where you will want the window to be. Then click any mouse button to actually position the window there.