Dedoimedo posted a tutorial explaining how to upgrade from Windows 8 to Windows 8.1, including preparations like data backup, system imaging and retrieval of the serial key from BIOS, windows updates, download and installation from the Store

If you are a sensible person like me, you will have waited several weeks after the official release of Windows 8.1 before attempting to upgrade from an existing installation of Windows 8. Indeed, you may even be waiting for this tutorial.

Let's kick it. Today, I will show you how you can upgrade from Windows 8 to Windows 8.1. We will do it step by step, a complete procedure, and we will make sure to handle all the important details, like personal data backup, windows updates, local and live accounts issues, the use of the Classic Shell versus the stupid Start Screen, and so forth. After me.

  How to upgrade Windows 8 to 8.1 - Tutorial