A typical VMware Sphere datacenter consists of basic physical building blocks such as x86 virtualization servers, storage networks and arrays, IP networks, a management server, and desktop clients.
Hence you need to configure servers (ESXi hosts) with required storage, network etc. You need to take help from your SAN/Network admin for the same
As per as management of datacenter is concerned : Datacenter can be created from VMware vCenter server., you can create datacenter object from either VI client , web client or by using APIs
Once you create datacenter on vCenter server, you can add configured servers (ESXi hosts) to created datacenter and manage your datacenter from single UI (either VI or web client)