DC's Trinity Storyline Question?

I know the storyline kinda suck but I have one question. How did Superman, Batman, and Wonderwoman become gods?    

It has to do with some pretty heavy duty reality warping.

What is this from?

What can they do in these forms?

They can fire energy from creation itself. This isn't well defined, but Krona (amped with the same energy) could bust a galaxy.

where exactly is this from