Now press Lens flare options. Now we're in the Lens flare panel. The flare intensity envelope is the most important thing here. It will decide what kind of an explosion you have. You can have a soft, thumpy explosion or a huge one, all depending on this envelope.
Lets try something.
So in a little time a the entire screen turns white. I've tried many different approaches to this. This one is just of the top of my head. If you experiment a little, you can probably come up with a much nicer intensity envelope than this one. That's all there is to it.