Choose a color
The Color Picker dialog appears. On the left, you can select the hue you want. On the right, you can see the main color's stripe. The square in the upper right corner displays the selected color. On the right, you can specify the color according to various color spaces (RGB, CMYK, HSB, Lab, Hexa), but let's keep to the easier way now. First, select a color from the stripe on the right, then click into the large field to select the hue. The starting color should be something dark, as this will represent dark colors in the picture. We chose a dark claret.
When you're done, click OK to return to the Gradient Editor dialog visible in Step 3. Now double-click the right-side color picker. The Color Picker dialog appears again. Choose another main color and a light hue. We chose a pale green. You can constantly track the results on the original picture.
Finally, click OK three times to close all dialogs, including Gradient Editor and Gradient Map.