It's better to avoid using pure white and black color in your work because they're very rare in nature. Most often you can see some light shades of blue, yellow or green instead of white and dark shades of e.g. brown instead of white. These shades don't look so harsh and are more realistic.

Enough talking just paint the mist :) Below you can see where I painted it to get the inspiration. Mist is behind the girl so avoid painting over her.

Step 7 - Blue Sweater

You've already get rid off two distracting things - too white bokeh and green moss. Another thing which I feel is quite distracting is the yellow sweater the girl is wearing. In this step you're changing its color from yellow to blue.

First you need to create selection of it. Grab the Lasso Tool (L) and create the mask.

With mask still activated add new adjustment layer Hue/Saturation on the top of all layers and set it as on the following picture.

Below you can see how the image looks after these seven steps.

Step 8 - Darkening the Background

This step is very quick. You're only darkening leaves and forest little bit. To do that add new adjustment layer Levels and set the Input Levels on 0; 0,72; 255.

Fill the layer mask of Levels with solid black color. Grab the Brush Tool (B), select some big, soft round brush and lower its Opacity on about 40%. Pick white color and paint over the background. On the following picture it's highlighted with red where I painted. As you can see I wasn't too precise and used very soft transition to get natural result.

Step 9 - Glow for the Girl

As you can see on the preview picture there is strong light source above the girl (butterfly). In this and following steps you'll start adding and changing light on the scene to achieve the same effect.

In this step you're focusing on glow in girl's face and hair. This step would be easier if you have tablet but mouse can work too. You may only need bit more patient to get nice strokes.

Add new layer on the top of all layers and name it e.g. GLOW ON GIRL. Grab the Brush Tool (B) and set the Master Diameter on 1- 2 pixels. Set the Opacity on 60 - 70%. Press Alt to activate the Eyedropper Tool (I) and pick some cyan bright color from the picture. Then start painting over the edges of her face and hair which should be lighter because of the glowing butterfly.