Why Create a Server?
A Desktop is basically a general purpose machine, geared for running the activities of the one user sat in front of it, whereas a Server is typically a machine that users do not directly logon to, but which provides services or functionality to one or more Desktops on it's network.
It's best to think of Desktop and Servers in terms of an analogy: Desktops are like a Handyman: they can do most jobs, but perhaps do not have the skills to do them as quickly or as well as a specialist in that area. Servers can be thought of more in terms of a Tradesman (-like a plasterer, carpenter, electrician, etc): they are dedicated to certain tasks and can do a faster, better job than the generalist Handyman.
Typically, we try to hive off functions common to all desktops on a network and instead put them on a dedicated Server, which will provide that functionality to it's Desktop clients. In this way, we free up resources on the Desktops, making them run quicker and more efficiently.
Some typical Server uses are:
There are two main reasons for setting up a server within the home:
As a central repository for data shared by all clients:
For example, you may want to keep your photos, music, videos on a single machine that can be accessed from the other PCs, your web-enabled Tv(s), Blu-Ray player, etc
To free up resources on your client PCs:
If your clients are slow, due to having to run various services like firewalls or anti-virus, it's possible to configure a server to serve up these functions, so you can remove them from your client PCs
Once you have built your server, you need to start by installing the Operating System.