This section of the Uncle Fester wiki covers the process of installing and configuring the basic TrueNAS operating system, including setting up an administrative user, configuring network ports, and indeed all other O/S level configurations that do NOT include storage or apps/VMs, and then stress testing all your hardware to confirmn that once you move your data onto the server it will provide a reliable 24/7 service.
Configuration of storage, network sharing of that storage, applications and VMs will be covered in later sections.