You can simply assign a number to the variable men_stepped_on_the_moon by typing it on the left side of the equal sign and the number on the right side of it.
Although this list didn’t include any woman so far, this might be about to change as Nasa announced there will certainly be a woman on its 2024 moon mission Artemis. The project is expected to cost $30 billion and you can read more about it here. )