If you look closely on the forest you can see some greener moss which is bit distracting. To make it less saturated and less distracting add new adjustment layer Hue/Saturation and set the value Saturation on -100.

Click on the thumbnail of the adjustment layer. Grab the Paint Bucket Tool (G) and fill the thumbnail with solid black color. Adjustment disappears.

Grab the Brush Tool, select some soft round brush and lower its Opacity on about 30%. Pick white color and paint over the green parts of the forest. Adjustment appears again in that areas and desaturates moss.

Step 5 - Cyan Tones to the Forrest

Now it's time to use Color Balance as I mentioned in previous step. You use it to create colder, more magical atmosphere.

Add new adjustment layer Color Balance and set it as shown below.

You want to change colors of forest, not the whole image. You need to change layer mask of the adjustment layers. Same as in previous step grab the Paint Bucket Tool (G) and fill the layer mask with solid black color. Then grab the Brush Tool (B) and paint with white over the forest to make the Color Balance adjustment visible again.

On the picture above you can see where I painted with white. As you probably notices I also painted over the woman's hair to give them similar tone as the background.

Your picture should look similar to the one shown below so far.

Step 6 - Adding Mist

If you've read more of my tutorials you probably know that I really like using mist to create magical or fantasy atmosphere in my images. And this image is no exception so in this step you're adding mist to the horizon.

Download the mist brushes listed in the beginning of the tutorial (or any other mist brushes you're comfortable to use) and install them into Photoshop. (If you don't know how to install them you can take a look at this tutorial.)

Create a new layer on the top of all layers and name it MIST. Grab the Brush Tool (B) and select one of the brushes you've just installed. Hold Alt to activate the Eyedropper Tool (I) and select some of the very light colors from the background.