To light the pilot light on a commercial oven, make sure the oven is off and locate the pilot light, then use a long match or grill lighter to light the oven. This requires creating an open flame near the opening of the pilot light hole.
The small pilot light hole is usually labeled on the bottom of the inside of the oven or inside the broiler.
If the pilot light is set to burn constantly, it should ignite when the flame is held to the hole. If the oven is designed to be lit for each separate use, turn the temperature dial on slowly while holding the flame next to the pilot light hole. This should cause the pilot to ignite. The pilot typically lights quickly, so be aware of the flame, and close the broiler and oven door.