Instructions:

The color that is on the brush head will be the color you use to paint.

By single clicking on one of the paint colors it will change the brush head to this color.

Single click on the mixing pad will make the brush turn to the mixing color.

Double click on one of the small paint colors will make the mixing pad into this color.

To mix color : by single clicking on the brush head it will add in the mixing pad a little of the brush head color.