Add Some Shadows
You're almost ready to add drop shadows, but first you need to expand the canvas around the edges of the photo. Select Image, Resize, Canvas Size. Switch the unit of measure from inches to percent, and then enter 110 for both height and width. Click OK. You should see that the canvas has expanded, and a transparent border should surround the edges of your photo.
Now it's time to experiment with drop shadows. In the Effects palette on the right side of the screen, click the Layer Styles button (second from the left) and then choose Drop Shadows from the menu. Now you can drag any of the drop shadow presets from the palette to your photo. If you don't like the one you dragged, replace it with another. When you find one that suits your image, save your finished product.