First download this photo:
http://www.freedigitalphotos.net/images/Women_g57-Girl_Relax_p3842.html

it is always good to keep a copy of the original image in a layer.

I will now adjust the color of the photo to a dark tone:
go to Image - Adjustments - Curves:
curves

With the Pen Tool draw a white shape like in the picture below

aura1

Now you have to duplicate this layer and rasterize it. Go to Filter - Blur - Gaussian Blur and set the radius to 2,5 pixels. Delete the middle part to see the face of the girl.
Now duplicate this layer and with gaussian blur set the radius to 4 pixels…
Duplicate again the layer and with gaussian blur set the radius to 6 pixels. Go to Blending Options and choose the Color Overlay : 0084ff, opacity 100% , blend mode : normal
You can actually play with the size of the initial shape if you want to obain a bigger aura…or you can choose different colors for the aura layers if you want a multi color aura.

This is my the result:
aura2