Starting the generation

Once you use menu TimeTable - Generate new the following dialog will appear:

If you have not yet tested the timetable, or you made a significant changes in the entered data, it is a good idea to test it every time before the generation. Just click the button Test the timetable. Why to test the timetable?

If your timetable passes this basic test, then you can try to generate your timetable.

You can also change the generation parameters. See these articles:
Constraints relaxation
What does the complexity of generation mean?

See also:
What is cloud generator?