Once you've installed the PLOT UPI macro it is automatically loaded each time that you start an L-Edit session. You can launch it from the Special pulldown as shown.
Note - Before clicking on the PLOT macro you should have turned on the layers you wish to plot and turned off all other layers. If you have a particular area you wish to plot it is easiest to zoom in until the this area occupies your entire screen. This is not required - from within the PLOT macro you still have some choices over what area to plot. Once you start up the PLOT macro, unfortunately, you are unable to PAN and Zoom or change your displayed layers....