Go to Select > Inverse.

Add new adjustment layer Curves on  the top of all layers and set it as on the following image. As you can see only borders of the image are darker.

Step 9 - Adding Girl

Download image of girl listed in the beginning of the tutorial and grab it into your photo manipulation. Place it on the top of all layers and name it GIRL.

To blend GIRL properly with the rest of the image you need to lower saturation and make it darker.

Add new adjustment layer Vibrance on the top of all layers and set the value Vibrance on -70. Create clipping mask from this adjustment layer to adjust only GIRL and not the rest of the image.

To make GIRL bit darker add new adjustment layer Curves on the top of all layers and set it as you can see on the following image.

Create clipping mask from this adjustment layer too.

On the image below you can see how your photo manipulation should look like so far.

On the image below you can see how your photo manipulation should look like so far.

Step 11 - Adding Shadow

In this step you´ll add shadow under GIRL to make it more believable she´s really there.

Pro tip: When creating photo manipulation remember that every object you place into your image should have some sort of shadow.

Add new empty layer below GIRL and name it SHADOW. Grab the Brush Tool (B), select some soft round brush and set its Opacity on 100%.

Press Alt on your keyboard to activate the Eyedropper Tool and pick some very dark color from your image. Now paint shadow similarly as you can see on the following image.

Step 12 - Creating Mist

In this step you´ll add mist to your photo manipulation to create more magical atmosphere.

Drag fractal1.png from the beginning of the tutorial into your photo manipulation. Place it on the top of all layers and name it MIST.

To blend it well with the rest of the image lower its Opacity on 60%.

Add layer mask to MIST. Grab the Brush Tool (B). Select some soft round brush, set the Opacity on 80%. Pick black color. Make sure layer mask of MIST is active by clicking on it.

Paint over the areas you want to hide. See image below for guidlines where you should paint. These areas are highlighted with cyan color.