Pour the paint you want to mix into the bucket, if they are the same color. If the paints you are mixing are not the same color, add the light-colored paint first and add a drop or two of the darker color as you mix until you get the desired color.
Attach the paint mixer to the end of your drill.
Plug in the drill and place the mixer into the paint. Turn on the drill.
Move the drill around in the paint until the color is even. If you're adding a darker color, drip it into the mixing paint until the color is even. If needed, add more paint until you get the color you want.
Turn off the drill once the paint is evenly colored and mixed thoroughly.