When the knurled ring is at 
push
the lever towards the dashboard (stable position).
The warning light 
on the instrument
cluster will come on.
Pulling the lever towards the steering wheel again, the main beams are turned off and the dipped beams on.
See also:
Number plate light
To change the bulb, proceed as follows:
❒ release the tab (A) and remove the cluster;
❒ turn the bulb holder (B) anticlockwise and remove the bulb (C). ...
Boot light
To replace the bulb:
1) Remove the lens A-fig. 39 as shown by the arrow.
2) Open the bulb holder B and remove the bulb C (clipped in).
...
If an interior light burns out
For the type of bulb and power rating, see “When needing to change a bulb”. ...