What must you do if you want to turn right at traffic signals where a green light is showing?

The correct answer is: Yield to oncoming vehicles.

In New Zealand, when the green light is on and you want to turn right, you must yield to the oncoming vehicles that are going straight. This is because New Zealand drives on the left side of the road, so turning right typically requires crossing the opposite lane, necessitating special attention to oncoming straight vehicles.