What are the requirements for light in portrait photography with black background?

You can use naked lights to score three or seven points, and add a front light with less power than the main light to make up the light. The black background is more prominent, and the fortitude of men and the femininity of women can also be displayed with background light. You can add a fill light or ambient light in front to create a silhouette effect, depending on how you want to show it.