Photoshop/101basics/The Basics/Workspace/menubar/layer/layers effects/gradientoverlay

=> Photoshop Tutorials => Photoshop 101 - The Basics 
=> Photoshop Layers Basics ==> Layers Style Effects ==> Gradient Overlay Effect

Gradient Overlay Effect

Blending Mode

Opacity This determines the density of the gradient

Gradient Here you can change the gradient color

Style The gradient style, radical, linear, Angle, Reflected, and diamond.

Angle The angle in which the gradient would be applied.

Scale How much the colors are interacted, the less the percentage, the harder the gradient.

Preview This would show you how the Gradient is applied

A sample of the Gradient Overlay is: