Edit Your Traveller SubSectors and create Maps!
Select dark or light background or select one of the other ones with stars and nebulas. You can also select a transparent background so that you can add your own backgrounds.
Select names for the neighbouring subsectors. (Enter a space if you want a blank name.)
It is important to keep the old sec format for your subsector. The guide at the top will help you. Do not remove the guide!
Right-Click and select save as!