Aedan929 :
I set up my whole home network which is pretty big with switches, and security too so I'm pretty sure I know what I'm doing!
No offense, and it's commendable to WANT to undertake an endeavor like this, but honestly, as mentioned, if you KNEW what you were doing, you would NOT need to come here and ask. There are a good many WORLD CLASS IT people that frequent these forums, two of which answered you already in this thread previously (And have probably had at least one hand, probably two, in many of the systems that keep other countries that would like nothing more than to shut down essential systems in the US, from doing so, as well as many other national security related projects), and I can assure you that none of them need to ask questions on how to set up a big network, because they KNOW what they are doing.
More importantly, just being able to buy some hardware and plug some cables in at home is nothing like configuring a workable network in a business or mission critical environment. There is far more to worry about than just a few switches, some cables and a server or two. Switches, wire runs, hardware firewalls, racks of servers, workstations, databases, encryption, protocols, software firewalls, routers are all necessary and must all be configured correctly from both a hardware and software perspective, and you'll also need to know how to manage the credentials and permissions to and from all those devices.
All of which needs to happen before you then must configure the security of the network using sandboxes, encryption, firewalls and other methods of adminstrating the network. If there is anything I just said that you don't fully understand, and you've already taken on this project, my condolences to you. I have 30 years experience with small business and home networks, and I wouldn't undertake a project like that for the simple fact that it's far more complicated than an untrained individual could ever hope to accomplish without the help of a professional.