Open the hood of the gas grill.
Turn on the gas by turning on the gas cylinder tap.
Start a burner by pressing in the control knob, turning it as much as it goes counterclockwise. When the burner lights up, you hear a ticking sound, but to be sure, you can keep holding the knob for a few seconds.
Then repeat this for each burner that your grill has.
When the grill is lit, close the lid and let the grill warm up for 10-15 minutes. After that, you can adjust the heat to the desired temperature and then just start grilling. Remember that you should not grill on the highest heat when the lid is lowered.
When the grilling is done, turn off the grill knobs and turn off the gas cylinder tap.