There is no definitive answer to this question, as the process for turning on an outdoor heater can vary depending on the model and make of the heater. However, in general, most outdoor heaters can be turned on by igniting the gas supply using a match or lighter and then using a knob to adjust the flame height.
If you're not sure how to turn on your particular model of outdoor heater, it's always a good idea to consult the owner's manual. Once you know how to turn on the gas and adjust the flame, you can enjoy the warmth of your outdoor heater all season long!