Some Fog Lighting/Photoshop help.

[konterganon]

well, i dont use gimp, but from what i can tell your brush settings seem incorrect.
the edges are still much too hard. dont know how the option is called in gimp but in photoshop its called "feather". it fades out the edges of your brush so its much smoother.
here a screen of one of my light effects (quite heavy)


as you can see, the fadeout is much smoother.
try to achieve something simililar by playing around with the brush settings