Now we'll use a levels adjustment layer (Layer>New Adjustment
Layer>Levels) to bring out the basic shape and color of the explosion. Put this layer above all layers.
Your going to adjust multiple channels, including the overall
RGB channel. This is very rudimentary now, you may want to come back and change it at the end.
First adjust the RGB channel middle input level so its skewed
On the Red Channel, bring the left adjustment slightly to the right, drastically bring the right handle left, and skew the center handle towards the right.
On the green channel, bring the left handle to about the center, drag the right handle to about 3/4 and skew the center handle towards the left.
Again, this is done to taste and will depend on how you've set up your own image. Consider the values shown in the images as a good start for a red-orange explosion.
Remember, make sure the adjustment layer is positioned above all other layers.