You can use the calendar to set appointments just by dragging and dropping them into place.
Start by navigating to the Unscheduled Tab to the right of the calendar.
Anything without an appointment schedule will be listed here. To easily schedule these, drag the event onto a time on the calendar. For instance, if you want to schedule it for 3:00pm on Wednesay, go to the Day view, and drag and drop that event on that time slot. The appointment will then be set for that time, and on that day!