Download the app from the apple app store or google play
Login using your work email and supplied password
You will see the availability screen
Updating availability is simple just click and hold, then drag down to select the time you want to make Unavailable.
If you want to remove a time you have previously made unavailable hold it down.
You can view the calendar in daily or weekly mode. Switch between the two screen by clicking the 'Switch to....' button at the top of the calendar.
