Microsoft will not update the original DirectX SDK until June 2010. Afterwards, the new version was integrated into the Windows SDK.
Find an upgrade guide on Microsoft's blog: http://blogs.msdn.com/b/chuckw/archive/2013/07/01/where-is-the-directx-sdk-2013-edition.aspx.
It is written in great detail inside. I'm here to pick out important things.
Windows SDK 8.1 Download: https://msdn.microsoft.com/en-us/windows/aa904949.aspx.
Help document: https://msdn.microsoft.com/en-us/library/windows/desktop/ee663274 (v= vs.85). aspx.
You can also download offline documents in VS and download Windows Desktop App Development.
Instance download: http://blogs.msdn.com/b/chuckw/archive/2013/09/20/directx-sdk-samples-catalog.aspx.
Or in the https://code.msdn.microsoft.com/ Search inside.