Working with colors and materials : Applying a color or transparency gradient with the Gradient Fill tool
 
Applying a color or transparency gradient with the Gradient Fill tool
The Gradient Fill tool lets you interactively apply a gradient to the canvas, a selection, or shape. You can adjust the colors, gradation, and transparency, as well as the direction, directly in the image window.
By default, the Gradient Fill tool applies the last gradient selected in the Material Properties > Gradient page, and modifies it with the current settings in the Tool Options palette.
You can adjust the overall transparency of a color gradient by creating the gradient on a new layer and adjusting the transparency of the layer. For more information, see Setting layer opacity.
You can adjust the transparency of individual nodes (opacity stops).
An interactive gradient fill line appears onscreen when you use the Gradient Fill tool.
To apply a color gradient with the Gradient Fill tool
Edit tab 
1 On the Tools toolbar, click the Gradient Fill tool (grouped in a flyout with the Flood Fill tool)
2 In the image window, drag across the canvas, a selection, or an object, to set the gradient line.
Note: By default, the last foreground gradient selected on the Gradient page of the Material Properties dialog box is applied.
If you right-click and drag, the last gradient selected for the background swatch is applied.
3 Do any of the following to customize the color of the gradient:
• To adjust the angle of the gradient, drag the rotation handle .
• To add a color, drag a color swatch from the Materials palette to the gradient line.
• To remove a color, drag a swatch away from the gradient line.
• To change a color, click a swatch on the gradient line (a blue swatch outline indicates that it is selected), and from the Materials palette, drag a new color swatch to the selected swatch, or click the Color Picker on the Tool Options palette, and choose a color.
• To adjust the transition between colors, drag the swatches along the length of the gradient line.
• To change the gradient type or to invert the gradient, adjust the controls on the Tool Options palette.
Note: If you can’t see the end of the gradient line, zoom out.
4 To adjust the transparency of the gradient, on the Tool Options palette, mark the Opacity stop check box, and do any of the following:
• On the gradient line, click an opacity stop, and adjust the Opacity setting on the Tool Options palette.
• To add an opacity stop, click the gradient line.
• To remove an opacity stop, drag the selected node away from the gradient line.
• To change the transition between opacity stops, drag the node along the length of the gradient line.
5 To return to color swatch editing, on the Tool Options palette, mark the Color stop check box.
 
If you want to adjust the overall transparency of the gradient fill, in the Layers palette, you can create a new layer before you apply the gradient fill, and drag the Opacity slider to the desired percentage.