How to use the sink
To use the sink, turn on the water pump switch, this can either be the third or fourth button (left to right) near the bedding compartment OR under the sink, inside the cupboard - look for the button with a tap above it.
Your Beach is equipped with a 40L clean water tank and 21L waste water tank underneath the van.
How to use the stove
In order to use the stove you have to turn on the gas tank by rotating the lever on the cupboard, underneath the stove, so the gas supply is enabled. After cooking turn the gas lever to its original position.
Other relevant articles:
How to refill the fresh water tank
How to empty the waste water tank