Complementary colors are simply the opposite colors in a color wheel, and opposite colors provide you with the highest color contrast in a composition. Let's take a look at a color wheel..
( Image source: Wikipedia )
I keep the color wheel image on my mobile phone, to reference it when composing a photo.. If you want the highest contrast and image pop, you need to choose complementary colors for the different elements in your composition. How good is the background color? Will a color gel on one of the lights be better? Do I need different color props? .. and so on. No rush, you need to get the photo you like.
Of course, there are color wheels with more colors, if you want to see more options & perhaps get more ideas.
Let's go over some samples