Ariston gas water heater - I don't know how to light a candle.

Hello. Usually someone else dealt with the problem of hot water in my house. Right now, I have to be on my own and I'm not doing very well. The candle in the heater went out on Tuesday. Since then, I've been trying to light it properly, but things go wrong all the time.
This is an Ariston brand heater. I don't know the exact parameters. When I push that big knob into the spark position, I sometimes manage to make a gas leak. Then I press that little black button and there is a light flame underneath. This operation allows you to turn the knob, as previously you could only select two positions. However, when I run over any of the numbers, I hear a loud noise and the flame underneath looks like a torch. After a while, everything goes blank.
I also tried to leave the heater on that little flame without turning towards the number, but after 30 minutes the tap water was still cold. I'm not sure, but these numbers seem to be responsible for the water temperature.
Yesterday, after turning on the small flame, instead of turning the wheel right away, I pressed it down and only then turned it to number 3. I don't know what went wrong, but the heater seemed to explode inside. I turned everything off and never approached him until now.
I am addressing all people here, asking for any advice. Maybe someone will explain to me step by step how to safely start this heater. Pretty please.

It's best to ask a neighbor to help you, but I'll try to help. Turn the knob to the left. Press the knob and activate the igniter. After lighting the flame, keep the candles pressed for about 10 seconds. then let go and check if the flame is burning. If it is not burning, repeat the operation. If so - turn the knob clockwise to the required temperature, If there is an explosive ignition, call the service - the heater requires cleaning. Good luck.

Thank you for your response. I just asked someone who knows about it for help. It turned out that the heater needed cleaning. The method you described is correct and helpful. Thanks again. (;