A week ago, Danganronpa 3 Despair Arc released its seventh episode. Coincidentally, the point it stopped at was immediately before the events of Danganronpa 0. I imagine that they'll simply gloss over the events of Danganronpa 0 and assume that you'll have read them (since it's readily-available in Japan and it's been spread online for anyone to read for free in the west).
Thing is, I didn't like Danganronpa 0. It's 270 pages that's mostly fluff that doesn't add a whole lot to the story.
So I wrote a summary for it here:
http://kimoforce.tumblr.com/post/149557943674/danganronpa-0-summary
Danna requested me to leave it on the forum.