I saw that you used LR to edit the photo. You can suppress (darken) the background using the Adjustment brush. I'd brush over the entire photo and darken it then erase the brush effect on her. I used Photoshop and created a mask for her then used a multiply blend to darken the background. The trick is being able to create the mask effectively and efficiently. The topic to search would be Photoshop layer masks. The LR Adjustment brush is faster and easier but less precise.
Here's a down-dirty way to approach the skin color issue:
View attachment 124937
IN THE sRGB COLORSPACE (numbers will change with colorspace) we can ask the question, what color is human skin? I called this down-dirty because we're going to make it really simple and use just a single value.
(Better precision will come from using denser data. Here's a good tutorial from Andrew Rodney.)
Back to down-dirty; we can calculate an average for human skin. For the human race at large (sRGB colorspace) it's a hue value of 20. Variation is less than one might suspect. Asian = 22, African/American = 20, Caucasian = 19. Individual variations from the average are also less than one would suspect. So here we have a Caucasian strawberry blonde (-1) who is still very young (-1) = 17. That doesn't mean this child meets that average specifically but without a WB reference for the shot it's a best guess and you can see that's what I did. I put the photo in Photoshop and on the assumption her forehead should be hue = 17 made the adjustment.
The variation to hue = 328 (50 points!!) is way past anything that would be naturally occurring.
Easiest way to solve this is to shoot a WB reference and/or set a custom WB from a reference. I use a piece of white Styrofoam cut from the bottom of a food tray.
Joe