To open the professor editor select Edit > Edit Professors... from the main menu. When you do, a small window will open which contains a list of all the professors you currently have in the professor database.
At the top is a small toolbar with three buttons. The first is for adding a new professor to the database, the second is for editing a current professor and the third is for deleting a professor. When you add a professor an input professor dialog box will appear allowing you to input the properties of the professor.
To edit a current professor either select the professor and click the second toolbar button or just double-click the professor. When you do, the same professor dialog box will appear with the professor properties loaded. Simply make the desired changes and select the OK button.
Once your courses have been input they will show up on the professor list in the course assignments window, as shown below.
One technical note about professors. Professors are linked to the schedule so if you make a change to the professor information the courses assigned to them will stay the same. Also, if you delete a professor any of those classes that were scheduled would be removed from the schedule completely.