Apparently the default vnc window is a simple terminal. To get a graphic window, you need to edit the xstartup file in the .vnc directory. To view that file :
Note the period before vnc. That makes it hidden for most purposes.
The file will suggest that you uncomment (remove the starting #) on two lines for a "normal" (graphic) login. As stated in the tutorial, you may want to change the last line in the xstartup file from twm & to something else.