You can also add an appointment that lasts all day.
Press on the cube "Calendar".
Then press the button "Add appointment".
Choose a calendar at the top of the list.
Give the "Appointment lasts all day" a checkmark.
Fill the 'Day of the Appointment' in.
Fill in the "Description".
Press the "Ready" button.
The appointment has been added to the top of the day and month view in the calendar and will be displayed in the color of the chosen calendar.