for real looking flame on the torch head shoot fire with a black background and import it.. then key out the black …
if you are just looking for the torch flicker on the walls of the enviroment make the layers you want to show it on 3D then create two cone light layers one yellow one orange.. or wahat ever colors you want.. place them size by side near where you guess the torch light is eminating … click cast shadows on (thats in your material opptions of the light layer) then.. on the intensity value create a random series of key frames raising and lowering the intesnity as you like the look..