suppose i make a flame in AE
and put it together in a video of my hand
basically me holding a flame, how would i change the colors of the areas that are affected by the flame's glow.
i mean the flame should give a glow and the area of my hand that glow doesn't reach should be darker
how do i change these environmental or background lighings in AE
I would try using an adjustment layer with a feathered mask on it. Track the mask onto the hand and then you've got an isolated area that moves with the hand. Apply lighting effects to the adjustment layer to suit your needs.
Work in inverse! Shoot in normal daylight, then darken the areas not affected by the light of the flame or casting shadows from it. Using color corrections it's easily possible to match the tint of the surroundings to that of the flame. Also check Andrew Kramer's website (videocopilot.net). In several of his tutorials he explains how to create light halos and similar effects, e.g. the one with the force field on the street.