Ich verstehe diese Heizung nicht. Irgendwelche Hilfe?

I have called the museum…

1. Turn the temperature dial to the ignition position (marked with a spark) and push it in.
2. Simultaneously press the ignition button and keep the temperature dial pressed for approx. 10 seconds until the heating element is sufficiently warm (operating status display showing green).
3. Turn the temperature dial to the desired room temperature (position 3 to 4 corresponds to a room temperature of approx. 20-22°C).
4. To turn off, turn the temperature dial to the „off“ position (marked with a dot).
5. In the ignition position, only the pilot light is lit.

(I am not seeing the status indicator in your photo, but the principle is the same: turn the dial to „ignition“, keep both it and the ignition button pushed in for a few seconds until the flame is lit.)