This switch is the master for the hob, it can be switched off here so you can use it as additional surface space while not hot.
Press and hold the power button to switch on (making sure the master switch is turned on)
Select the hob ring you want to heat by pressing the corresponding circle.
Once selected a red . will show up next to it you can then use the - + buttons to choose how hot you want it to get. When a hob is hot after use a h will be displayed next to the corresponding circle.
There is an optional timer setting if you press the clock button, then select the length of time you wish the hob to be on for.