Make a new document, 500x500 pixels, white background
With the rounded rectangle tool, make the shape of the button. Now CTRL+click on the shape to bring the selection. Now delete the shape and make a new layer so you'll have only the button selection on a new layer.
With the gradient tool, apply a gray-white gradient on the selection:
Go to layer style and apply an outer glow black, 2 pixels like in my example:
In the same window, apply a Bevel and emboss with these settings below: (remember, do not use "Global light"). Your button should look like this:
CTRL+click on the button layer to bring again the selection. With the selection tool, substract the bottom portion in order to have only the upper one active. Fill it with white.
CTRL+T to enter the free transform mode and scale it about 90%.Now apply a gaussian blur. I used 3.3 pixels. You're done.
More Tutorials: 
