Click on the "Create a New Layer" button in the Layers pallet. Drag the new layer to the bottom of the stack.

Press Ctrl+Backspace to access the Fill tool. With this tool, you can fill the layer with any color you like. I'm going to select the 50% Gray for this step. Click OK when you have your color selected.

Finally, we're at the last step where we can reposition the photo. Select the layer mask then select the move tool from the toolbar. Drag the frame around to position it in a creative position where part of the subject is outside of the photo.

To add a more three dimensional effect, you may distort the image. To do this, press Ctrl+T to activate the Transform tool. Now hold the Ctrl key and drag each of the four corner to skew their position.
