Step 2. Click on the GLOW layer to bring up the layer properties panel. make your blur RADIAL and make your Blur Radius 2 or 3. Tick 'Invert Matte'
Step 3. In the same panel play around with the color values, and push the alpha to a value of 255 for maximum effect (it's actually best to do this with the scene in render view, so you can see what you are doing, and how the effect is working)
Also - create keyframes to change the color values in the timeline for a 'flashing' explosive effect
And that's it. You can also us this process with the SHADOW effect layer to tint your entire scene