What I have, personally, done in this kind of situation is take a close look at their character sheets, what can they do, what are they good at, and write an 'easy mode' adventure where they get a chance to use each of their abilities.
Once they come to a point and don't instinctively realize what they're supposed to do, gently ask the relevant player if they can do anything about the situation. Beyond that, don't forget to include basics regarding your GMing style.
For example, if you use a lot of traps, start with a few light and relatively harmless traps. Enough to wake them up to the idea that not everything that can harm them can be seen, should help them get them used to searching.
You can also show off some tactics that can be useful for anyone by making the monsters use it. Aid another mid-fight, flanking, readying actions, et cetera. Make sure to let the players know that those are things anyone can do.
It's fine to be a bit railroady during such a tutorial adventure, especially with newer players, but don't forget to include the roleplaying parts as well.
I don't think you have to hide the numbers for what you are doing, but rather just how you get them.
I've made my game more player facing, i.e. they players roll all of the dice. But I've also made it more narratively driven, i.e. the players don't invoke their powers, instead, they describe their actions. (Taken liberally from *World games)
I did this in response to exactly the problem that you're having- that DFRPG can be overwhelming at times. So how does this work?
The first part about the GM not rolling takes a lot off of the GM's shoulders, and makes things faster. You then use this savings to spend the time to interpret the players' actions, and trigger them based on the narrative for the players that are less familiar with the rules. Rotes help a lot with this.
So, the only things you have to explain to your player are- the rotes that you help them design with their characters, and the meaning of overcasting vs standard casting. Once you've done that, the player describes what they are doing, i.e. casting their rote, or putting more effort into it or really pushing themselves. You look at the numbers behind the scene, and give them the target. They roll... and describe what they are doing to invoke their aspects as needed, since they know what they need to make the roll.
This way, they are eased into the aspects of the game that have to do with Fate, while the crunchy things of magical manipulation are kept behind the scenes.
In summary, let them describe it in the narrative, you do the heavy lifting, then let them roll against a static number, invoking aspects as needed to make the roll if they want to so with more narration.
Best Answer
I remember when I was a little bitty Hero player...
If you're starting the campaign from scratch, I think it's actually better to ask the experienced players to tone it down. They're going to be able to get into the more complex tweaks with experience points anyhow; it's not going to hurt anyone to start simple.
If you're integrating a new player into an existing campaign, it's going to be tempting to let the experienced players make the character for the new player. Or at least give a ton of advice. I think that can really tip into being intimidating, however, so you've got to be careful there.
What I'd do in that case is look for the easy powerful archetypes. You don't need to be super-clever to get a lot of out of a Strength-based brick, or a blaster. Martial artists are more finicky; steer the new player clear from those. This limits choice a bit, but it makes for easier assimilation.