I know this looks really bad, but I started with your edited (darkened) image, I did it really quickly and it's the process that you'll want to see.
The first image is your edited image.
With the second image I just darkened and added a blue tint to the outer 1/3 of the image. I also added a simple feathered mask around the fire with a orange tint with higher brightness and lowered contrast. If I were to spend more time on this I would make the mask not a simple and round, but smoothly uneven.
With the third image, I added highlights using an adjustment layer with higher brightness and an orange tint, then just masked out parts that I though should be bright and feathered them out. I used a yellow-green colour the further away the highlight I was concentrating on (some of the highlights that I've done are a bit too strong). This shows that the fire is casting light on not just the floor.
In the last image I did the same as above (using masks), but this time I used a black colour, to add shadows (underneath boy's leg / where arm is at angle). This gives the impression of only one light source. A problem with my quick mockup is that there's not enough distinction between highlights and shadows, especially on the guy with the green shirt on. And my highlights don't look like they're coming from the fire, they look light they're coming from the left of the picture (oops
, you get the concept though)
What you might also want to do is to mask out a few objects on the ground, and then add a elongated black mask over them, so it looks like the fire is casting shadows.
The hard part is animating everything to make it look real -- the fire, the light from the fire has to flicker, the shadows will change, tracking everything, making the shadows change to the fires shape etc.