Step one:
Make a new transparent document . Take the Elliptical marquee tool and make circle in the left side of the layer, fill it with 100% Black. Duplicate the circle and drag to the right side. Drag two horizontal guides towards the circles edges. Take the Rectangular marquee tool and complete the button shape by drawing a rectangular selection inside the circles, fill with black. Merge all layers if necessary.

Step two:
Hide the guides and load the layer selection by holding down the Ctrl key and click on the layer image in the Layers palette.

Step three:
Press Ctrl+H to hide the selection, Choose foreground RGB 25,116,1 (Hex #197401) and background RGB 52,246,0 (Hex #34F600) take the Linear Gradient tool, in the gradient properties dialog box choose "Foreground to Background" hold down the Shift key and fill it from up to down. Press D to reset colors to default.

Step four:
Use a 65 diameter soft brush with 25 spacing and paint some shadow around the shape.

Step five:
Make a new layer. Take the Rectangular marquee tool and make a rectangular selection for the button highlight. Deselect and Fill with white, deselect and Gaussian blur by 3.

Step six:
Zoom inside, press Ctrl+T to transform the selection, hold down Alt+Ctrl+Shift and drag the transform Uncurves 45 degrees to the left.

The finished look.