To start off, ensure you are on the main 'Metro Screen' as we will be starting from there. While on this screen you will be able to begin typing immediatly.
On the Metro Screen type the words 'Windows Update' and you will see a 'x Results Found' appear on the left pane of the screen. From here you want to click on the 'Settings' Tab and then Click on 'Windows Update'. Both of these can be seen in the provided Screenshot.
For Windows 8.1 To be Installed, you must have completed a specific set of updates. For the sake of simplicity, this walkthrough assumes you have NOT performed this update. If you are up to date with your Windows Updates, you are welcome to skip to Step 4. This process may require several reboots and revisits to this page.
Once you have no Windows Updates left to perform, we are ready to proceed with the 8.1 Update. This is done via the 'Windows Store' otherwise displayed as a Green Shopping Bag. (Pictured Left)
If you correctly updated your Windows in earlier steps, you should see a large Icon that says 'Update to Windows 8.1 for free'. It will be a very dominant tile and is very hard to miss. Once you go into this, it will give you a download button to begin your 'purchase'.
The Update will take some time to Download as it is over 3GB (3000MB) in size. This can be done in the background as long as you don't force close the Windows Store app. Once this is done, the install will take a while to complete.
That's It! Your machine is now Windows 8.1. Enjoy the additional features and speed that Windows 8.1 brings with it.
Thanks for reading, we hope it helped!