While the typical process for getting work booked into calendars is to create time estimates, or requisitions on phases, and then to drag these onto the calendar from the list you can also create the booking directly in the main scheduling interface without the need for either an estimate or a requisition. Click where the booking should start and drag to the end date / time - you'll see a highlighted area indicating where the booking will be created. Once you release the mouse button the booking details form will appear for you to fill in - client / job / phase / charge code must all be selected, and you can choose between all day and hours per day for multi-day bookings, just as you can for estimate or requisition based bookings.