You can open and close the air vents via the climate view in the centre display or physically using the thumbwheel beside each vent.
Opening and closing air vents via the centre display
Press the fan symbol in the bottom bar 
.
.Select the air vents you want to open or close.
Redirecting the air flow
Use the physical air vent knobs to redirect the airflow.
To close an air vent, press the same vent again in the centre display.
If you only have one air vent open, you can't close it in the climate view. Instead, press Climate off to close the open vent.
Tip
If you choose a specific air vent while auto climate mode is active, the climate system will change to manual mode. You can always go back to auto climate mode again by selecting Auto in the climate view.