Login into your workstation (enter user name, then password)  If Xwindows (the graphical user interface of Unix and Linux) does not start automatically type "startx" and return (CR)  A window with the heading "xterm" should open automatically; this window acts much like a Unix telnet session.  Type "xterm&" and CR at the prompt. The ampersand at the end is important, if your forget it you cannot use the window until the application you ran in the window is closed.  Now you should have two windows. In the first window type "Matlab" and CR, in the second "Netscape&" and CR.
Download dfield & pplane here:
In Netscape load the link above  Scroll down to the part of the page marked "For use with version 6.0 of Matlab."  Find the three links below this heading; dfield6.m, pplane6.m and ppn5ou6.m  Right click on the dfield6.m link and choose "save as"  In the pop up window, choose the directory where you will be running Matlab. Your home directory is fine.  Make sure that the file name is dfield6.m (retype if necessary  Click save/ok  Repeat the three preceding steps, replacing each instance of dfield6.m with pplane6.m. Repeat this process for ppn6out.m