On DHQ site, navigate to the schedule subsite and select "Schedule Admin Action", then select "Setup Shift Master"
Click on "New" to add a new Shift, when you hit add latest item link you will see a form where you can type the Shift Title like s1, s2....
Enter Rotation Length for that shift.
Select Multiple shifts or not. Multiple shifts are used to account for a split shift and is rarely used.
Enter the number of shifts per day value like 1, 2...
Hit save your new shift will be saved and display over.
Note you can change the saved Master records by just clicking edit.