There are two types of colour mixing: Additive and Subtractive. (see Colour basis)
Mixing primary colours together will create a secondary colour, a secondary colour with a primary colour will result to a tertiary colour.
The addition of black, or white will vary the colour tone and mixing complementary colour together will result to a desaturation of the colour, a neutral grey.
The practice of colour mixing is the best way to familiarize with the relationship existing between the different colours.
Notes: Colour mixing is particularly relevant when engaging in digital work. Often, there is a difference between what is displayed on a screen and what is printed.
Color and how to use it, 2010,By William F.Powel