The Square on the right is the Actual color and the Dot is the Rendered Color. You can change the right square to any color, and it will copy and render it. Press Space to Start the rendering process. The proximity variable is how close you want the rendered color to be to the actual color. But the Smaller it is the longer it will take.
Note: If you want to Remix the Project first Delete Everything that is on the Colors "Ready Only" list. Because scratch will not let you save a project with a Very big List