there´s a tutorial on how to make a very simple explosion on the help file in maya. its in the fluids section. if you dont want to do it you could open up the visor.
i think its in window, general editors, visor.
there is a huge list of different things. like paint effects, hair, trees, fluids etc.. find the explosions sections there theres 5 or 6. (maybe more) explosions samples. just middle mouse drag them onto your work area.

how this can be of some help to you.