The first step is to create your canvas. It can be any size you want you button to be. I’ve picked 200pixels by 100 pixels. Mine, of course, will be rectangular.

In hindsight it would be better to fill the entire canvas with your gradient we are about to create. I don’t no why but I [...]

Start a new document. Click on the [ Custom Shape Tool (U) ]

Choose ‘sign 4′ and draw this shape.

Making Layer Style
Double click the layer or go to Layers->Blending options and apply settings as shown.

Here is the result

In layers panel hold Ctrl then click on layer of shape to make a selection of it.

Now go to [...]