A new DM should (IMHO) try playing in a game of the specific system run by someone else first, even in a minimalist system like Fate.
The thing about Fate is that the jargon is generic fiction terms, rather than medieval fantasy or whatever. So you have to read the rules cover to cover before DMing, and make sure to jump forward and back to remind yourself of definitions etc. Once you get going, and are familiar with the two or three mechanics you can use, it's very liberating though!
If it's what I think it is, you should be able to start with Accelerated and then convert to Core if some things aren't working (i.e. it's too simple).