Translations:Windows Server 2012 R2/15/en

Select any version and click next, you can download a comparison PDF of the different versions.

Server Core Installation Installs the server without GUI (graphical user interface). Not recommended unless you know what you're doing.
Server with a GUI Installs server with GUI.

Accept the license agreement and click next.

Select "Custom: Install Windows only (advanced)", unless you are updating your older server and wish to save old files and settings.

Select the disk which you will install Windows Server to and click next (You can partition the disk later in whatever manner you prefer).

Wait for the installation to finish.

Define the system administrator password and click finish. When installing from network you also have to give the language, currency and keyboard settings again as well as accept the license and re-enter the installation code (you can skip the code part if you want to).

Wait for a moment while Windows readies your desktop.