Generate a plot with a second vertical axis. HAXIS= specifies the AXIS1 definition. VAXIS= specifies AXIS2 and AXIS3 definitions in the PLOT and PLOT2 statements. CAXIS= colors the axis lines and all major and minor tick marks. Axis labels and major tick mark values use the default color. VMINOR= specifies the number of minor tick marks for each axis. 
proc gplot data=reflib.minntemp;
   plot c2*month  / caxis=red
                    haxis=axis1 hminor=0
                    vaxis=axis2 vminor=1
   plot2 f2*month / caxis=red
                    vaxis=axis3
                    vminor=1;
run;
quit;