Photographers use colour all the time but do they understand it?
Colour can be quite complex. However, there are some simple principles that help you to work with colour. Like other compositional elements colour can change your picture in many ways. If you use it you can enhance your picture. If you are not aware of its significance you can spoil the impact of the picture.
These two videos provide introductory principles as an insight into understanding how colours work together and their effects within the image.
Colour in photography – The colour wheel explained
Complementary Colours in Photography