How to add new lessons in substitution online in mobile app

You can also add new lesson in subsitution via application. Select the day first, then list of substituted lessons (no problem, if there is none) and advanced option icon. See following picture.

In a new screen you can add all necessary data for your new lesson (choose Subject, class and group, teacher, clasroom and period). Because you are still in Substitution module, you can still select "the type of substitution" and note also.
In the bottom of the screen you can see all related timetables and your new lesson highlited. If everything is fine, confirm by "OK". New lesson will be added into timetable for selected day.