The Color Fill tool fills in similarly colored areas of an image with your chosen solid color.
Choose the Color Fill tool by doing one of the following:
Customize the Color Fill tool:
Color: Click the color well to choose a color or click to pick a color from the image.
Blend Mode: Click the Blend Mode pop-up menu to choose a blend mode.
Opacity: Drag the Opacity slider to adjust the transparency of the Color Fill tool.
Sample All Layers: Select Sample All Layers to make the Color Fill take into account the contents of every layer in your image, not just the selected layer.
Smooth Edges: Select Smooth Edges to naturally smooth the outline of the Color Fill tool. With Smooth Edges unselected, the outline will be a little more precise but jagged.
Drag on the canvas to fill in similarly colored areas.
The more you drag, the larger the area Color Fill tool will fill. If you’d like to fill the entire layer regardless of any existing colors in it, drag until the Tolerance value reaches 100%.
If you'd like to discard all the current changes made with the Color Fill tool, click the Reset button at the bottom of the Tool Options pane.