The Color Picker is divided into two tabs — Spectrum and Swatches. To use either one, select a layer of your image and click the desired color from the tab you open. If the Layers palette is not open, click the three stacked squares in the lower left of the Editor.
The Spectrum tab (color wheel icon) offers a high degree of control over color selection:
If you know the Hex code of the color you want, type it into the box next to the color dot (It looks something like this: #123456.)
If you want to choose a color manually, drag the circle on the rainbow bar to pull up different color ranges in the selector square. Then choose the specific color in the square.
The Eyedropper helps you choose exactly what color you want from another part of your image. Click the Eyedropper and hover over the desired color. Click on the color to apply it to the selected layer.
The Swatches tab (palette icon) includes a collection of preset colors for quick access and application. Choose a color that works with your design, then click it to apply to the layer you’ve selected.
If you're a Pro or Business subscriber and create a brand kit, your brand colors will show under Brand Color Palettes.