Navigation Panel > Administration > Colours
click on the button New
Give the colour a Name
Give the colour a Code for that colour (this is used when you allow the system to auto generate the child products)
Give the colour a Description
There is an Archive tick box that is there for down the track when you decide you no longer want to use that colour. You will only be allowed to tick this when there are no products assigned to this colour.
Click on button Save and Close
Repeat the steps above for each colour you wish to create to be able to be used by Styles