Go to the DJI website a look through the video tutorials for assembling the F450 and setting up the Naza. Very simple stuff to be honest, but the actual assembly process is pretty essential for understanding how your machine fits together and works. This is one of the reasons that I would normally recommend that new flyers (of any RC model) don't buy pre-built and ready to fly models, particularly pre-owned. If things go wrong on the initial flights and you built it yourself then you will already have an idea of what to look for, because during the build process you will have made mental notes about certain aspects of the assembly. If someone else built the model and you have never assembled one yourself then you really are left knowing nothing and only trusting the original owner did a decent job of performing critical assembly tasks ... such as soldering the speed controllers.
I had already built my own F450 with Naza before buying a pre-owned F550 which had only had it's speed controllers soldered and was otherwise unflown and essentially new. Having assembled an F450 I felt quite happy to pick up the pre-owned F550 and since the build had never been finished I was able to inspect every soldered joint and every screw before even installing my own Wookong-M. So it was pretty much like I built it myself anyway and pre-owned kit doesn't come along in the condition I described very often as in reality it was little more than having been taken out of the box and so was essentially like new.
Main things to get your head around with multirotors are the following :-
1. Prop replacement and rotational direction and understanding why they work the way they do.
2. How your model's electrics connect, end to end, from battery through to motor.
3. How your flight controller works, flight modes and in particular failsafe.
4. How to program your transmitter - channel assignment and direction and also failsafe programming.
If you've never flown a heli before then I strongly recommend you getting yourself a simulator and starting there and get an experienced pilot to spend some time with you on a buddy TX. Join an RC club.
