A Working Outline might be only an informal list of topics and subtopics which you are thinking of covering in your paper.
The working outline can be revised as you discover new material and get new ideas that ought to go into your paper.
Most word processing programs have outlining features with automatic formatting that make it easy to create and revise outlines.
It is a good idea to keep copies of old outlines in a computer folder in case new versions of the outline lead you in false directions that you will later have to abandon.