In order to generate back dated shift, first choose Area from left hand menu. Once calendar shows up, navigate back to date where you want to start your shift (use calendar controls).
Next, click on the past date in the calendar (24 Jun in example below), it will then prompt you to make a new shift. You can create one off shift for that date, or you can generate recurring shift by changing end date in Program Period.
In order to generate shift in past, click on the left arrow or choose the past date by clicking "go to" button.
Once you are on past date, say 14th march (in example below). Click on "Add Shift" and generate shift. Please read program for further reading.
Note: Do not click "Add Shift" button in order to generate past shift, as this will only allow you to select current and future dates.