Create the Button
Make a new layer, select the Elliptical Marquee tool, and Shift+drag within the image to draw a circle the size of the final button. Select Edit, Fill and fill the button shape with black.
Make a new layer, select the Elliptical Marquee tool, and Shift+drag within the image to draw a circle the size of the final button. Select Edit, Fill and fill the button shape with black.