The first thing to learn on the schedule is creating a shift. To create a new shift, simply click any open area on the schedule for the employee you want to create a shift for. (Shifts cannot be created in the past). From the shift creation dialog, you can set the start time and end time, add breaks and notes, and define the shift type. PTO shifts will not count in total hours or show up on the scheduled labor chart. You can read more about managing breaks here.
To edit a shift that has already been created, click on the shift you need to update and make your necessary changes. Don't forget to hit save to make your changes stick.