To schedule Vacation Time for your technicians, the best/easiest way to do this is via Calendar Events.
You can access this on the Dispatch Board. Tap the Plus button on the top right and select "New Calendar Event"
From here, simply fill in the required information such as the name and listed employees (if multiple are off at once) and choose your start date/time. You can also make this a recurring event if the technician needs to be off the same day/time every week: