To create the Lissajous plot, you select items from the menu as follows

DATA
  IMPORT
    ASCII
      SELECTION: lissajous.txt
     *OK

PLOT
  PLOT APPEARANCE
    TIMESTAMP
      Check the ENABLE box
     *ACCEPT

PLOT
  GRAPH APPEARANCE
  In the TITLES box:
    TITLE: Lissajous Curve
    SUBTITLE: x=sin(3t+pi/2), y=sin(4t)
   *ACCEPT

PLOT
  SET APPEARANCE
    In the LINE PROPERTIES box:
      COLOR: Red
    In the SYMBOL PROPERTIES box:
      TYPE: Circle
      SIZE: 10
      COLOR: Black
    *ACCEPT

PLOT
  AXIS PROPERTIES
    Edit: X axis    (probably already says this)
    In the TICK PROPERTIES box
    Major spacing: 0.2
    Select the TICK MARKS tab
    In the MAJOR TICKS box
      Check DRAW GRID LINES
    *ACCEPT

PLOT
  AXIS PROPERTIES
    Edit: Y axis
    In the TICK PROPERTIES box
    Major spacing: 0.2
    Select the TICK MARKS tab
    In the MAJOR TICKS box
      Check DRAW GRID LINES
    *ACCEPT

Now save the image:

FILE
  PRINT SETUP
    In the DEVICE STEUP box
      DEVICE: PNG
    In the OUTPUT box
      FILE NAME: lissajous.png
    *ACCEPT

FILE
  PRINT

  (This choice writes the graphics information to the PNG file.)

FILE
  EXIT
    
"Exit losing unsaved changes?"
  OK