You can additional commentary to your graph with XYOutS

After the XYOuts command you must add two numbers.  The first is the position along the X axis where the text string will be printed.  The second number indicates the location along the Y axis.  NOTE:  This line must be added after the Plot command has been issued.

XYOutS, 3, 9.2, 'Text goes here'
 
 For a complex example combining the use of XYOutS and POSITION, visit How-To site, Make Axis Titles Larger Than Axis Values