1) You create a Sprite object
2) After you click on the layout editor, the Image editor will open up
3) Right click on the Animation frames window and choose: Import frames/From sprite strip
4) C2 is clever enough to detect that your png has a single row of 48 images (Number of horizontal cells = 48, Number of vertical cells = 1). Press ok.
5) Setup the speed for your explosion (the default fps is 5 which is too slow in your case) 24 or so works nice.
You are done.
You can always overlay bright images with black backgrounds using either the Additive blend mode (in the effects properties of the Sprite object), or add one of the additive blend webGL effects (like Screen, Dodge, Lighten, Soft light...).
There is also the Chroma 2 webGl effect (search the forum) which works like keylight (in After Effects) or similar software that do color removal for Green/Blue Screens.