Pigment is generally a small molecule organic substance. The specific structure will not be examined in high school. All you need to know is that chlorophyll contains Mg element.

In high school, it is enough to know the functions of pigments, and the exam will involve pigments in chloroplasts and anthocyanins in vacuoles. The most common pigments in chloroplasts are to absorb light energy and convert light energy into chemical energy to generate ATP, and at the same time realize the photolysis of water to generate oxygen and reduced hydrogen.

As for anthocyanins, you can also learn about it. It is the reason for the color of plant cells and the maintenance of vacuole osmotic pressure, which is almost ignored.