If you want to upgrade not only VCM but also the OS underneath it, this is the recipe to look at. VCM 5.8.2 now supports Windows Server 2012 R2, and it's a good chance to perform an upgrade.
To start with this activity, you must have all the user accounts in place and they must have permissions as described in the first chapter. You must have a user apart from the service account, which may be your own account, with admin privileges on the VCM Collector server to perform the installation.
If you are using a physical server, then take a backup of the server with the tool you are using in your infrastructure; if that Collector server is a virtual machine, take a snapshot of the VM.
Take a backup of the databases so that if something goes wrong, you can get back to where you were before the upgrade. If you are not aware, you can get help from your SQL admin to take a backup of the databases.
You must have access to https://my.vmware...