How to install Windows 10 for free
This video will show you how to install Windows 10 for free on any computer that already has a licensed copy of Windows 7 or Windows 8 (except for Windows 8 RT version, which was only on a small amount of tablets).
To make sure you have either Windows 7 or 8, you can go to your computers properties, and it will tell you near the top.
Basically, to get the option to upgrade, you need to have all of the Windows Updates installed. For Windows 8, this means you also have to upgrade to Windows 8.1 (a free upgrade through Windows Update) before you can install the rest of the updates that will allow you to upgrade to Windows 10.
The most important update is KB2919355. This is what actually makes the Windows 10 option appear in the bottom right of your computer. Even after this update is installed, it can take several days before the option to upgrade appears.
Keep in mind that if you have not updated your computer in a long time, or you need to upgrade to Windows 8.1, then you may have to do several rounds of updating. So if the option for KB 2919355 isn't showing up, try restarting and checking for updates again, and then waiting a day or two and checking again if it still isn't there.
Check out my facebook at: / 198429346974010
or my twitter: / allhow2s
Or my website where I have a lot of other great tutorials (such as how to take a screenshot, or how to get the start button back on Windows 8): http://www.allhow2s.com