Start a new document 300 x 200 px. Use your prefered background color, I’ve chosed a gray gradient background.

Pick #181818 as background and #343434 as the foreground take the gradient tool and select radial gradiet and starting from the middle of your canvas drag towards one of the edges either left or right, top or bottom. You should have something like this.

Select the rounded rectagle tool from the sidebar. (You can also use a custom shape if you want).

Make a rectangle in the middle of your camvas the size you want.

Go to Layers, and make right click on you shape layer (in my case rectangle), then select Blending Options.

Now add these Layer Styles.

You click OK and now you should have something like this.

Create a new layer, name it bright, and make an ellipse over the middle top of the button, using the Elliptical Marquee Tool in the sidebar.

Then fill it with a withe color like this. (Don’t worry if it looks ugly)

Now holding shift, make right click over your shape layer for grab the rectangle as a selection, then go back to your bright layer and now, go to Select > Inverse or (CTRL+SHIFT+I)

Press the delete key and set the layer opacity to about 15%. You should have something like this.

Now write your call to action phrase, something like: Download, Free, Sign up, what ever you want. Fill it with any color then add these layer styles.I used Sign Up text on this Button

You should have something like this. A Call to Action Button.

Then you can ad a small element like an arrow or a plus it depends on you, to give it more value to your button.

Thats all, now you have a Call To Action Button, in some simple steps.

Via:How to design a great call to action button