This is a simple tool to pick colors from an image and create the CSS from the chosen colors.
Simply drag and drop an image to the field on the left and move your mouse around on the image to capture the color.
Click your mouse to pick a color and add it to your collection below.
Press the "Get Code" button to get an HTML document with all your picked colors to copy & paste.
You can also watch this screencast for all the information needed.