Final Image

The original photo

Step 1: Add a simple border to the image.

Go to Filter > Decor > Add border
Border X size and Border Y size: 8
Border color: f2f2f2
Delta value on color: 1.

Step 2: Add gradients to get a real photo look.

Add a new transparent layer.
Set black as the foreground color.
Activate the blend tool. Change the gradient to "FG To Transparent"
Now draw the gradient at the upper left corner. Start a the corner and drag inward.
(If you've made the gradient to big you'll need to undo the gradient before trying again).

Change the opacity of this layer to 15.
Add an other transparent layer.
Set white as the foreground color.
And draw the gradient at the lower left corner. Start at the corner and drag inward.

Change the opacity of this layer to 40.
Go to Image > Merge Visible Layers (don't use Flatten Image !).

Step 3: Give the photo some more space.

In one of the next steps the photo will be rotated. By make the canvas bigger the photo will have enough room to be rotated.
Go to Image > Canvas size.
Add 120px to the height (height and width are linked).
And press the center button.
Add a new layer and fill it with white and drag this layers so it places under the photo layer

Step 4: Give the image a nice shadow.

Before creating the shadow we'll distort the photo so we'll get a nicer more realistic shadow.
Duplicate the photo layer and activate the original photo layer.
Go to Filter > Distorts > Lens correction and use the following settings.
(You need to change these values depending on the size of the image.)
Main: 4
Edge: -20
Zoom: -10
Brighten: 0
X-shift and Y-shift: 0
You don't see that changes because of the top layer. When the top layer is hidden you'll see this.

Go to Light and shadow > Drop Shadow.
In the example image the following values are used, but feel free to change them.
Offset X, Offset Y: 8
Blur radius: 15
Color: Black
Opacity: 80.
The disorted photo layer is no longer need so delete this layer.

Step 5: Rotate the photo.

Rotate the shadow and photo layer.
Go to Tool > Transform > Rotate.
Set the angle to 9.
And do the same again with the other layer.

You could have merged the shadow and photo layer. But now you can still move the shadow or lower the opacity a bite. In the example I've used the Move Tool to move the shadow layer a few pixels and the opacity of the shadow layer is lowered until 50.