How to Print Plots from Gnuplot
First you prepare your plot as you want it in gnuplot. 

gnuplot> set term postscript     (will produce postscript output)

gnuplot> set output "" (output will be written to the file, or any name you use)

gnuplot> replot                  (recreates the plot but you don't 	
                                  see it, it goes to the file)

gnuplot> set term x11            (resets the normal gnuplot
                                  so you can do more plotting)

Now you have a postscript file named  containing 
your plot.  

You can view it 
    with ghostscript:      or     with ghostview:
    UNIX> gs           UNIX> ghostview

    or print it:
    UNIX> lpr