GETTING WINDOWS 10
If your computer is already up to date:
If your version is Windows is as up to date as it can be, you should see that a Windows icon has appeared in your task bar. (If you don’t see it by Wednesday, Microsoft has some unfortunately complex instructions on how to make it show up.) Clicking on the icon will open up Microsoft's Get Windows 10 app, which allows you to sign up to download the new OS and determine if your computer is compatible. Enter your email address into the system, and from there you're pretty much set. Now you just have to wait.
If your computer isn't up to date:
Once you're on the latest version of either operation system, the Get Windows 10 app should be available, and you'll be able to grab the free update.
If your computer is really out of date:
Windows 10 has the same system requirements as Windows 7 and 8, but those requirements are still substantially higher than those for earlier versions of the OS. Make sure that your computer meets these minimums before updating:
RAM: 1GB for 32-bit or 2GB for 64-bit
Storage: 16GB for 32-bit or 20GB for 64-bit
Graphics support: DirectX 9 or later with WDDM 1.0 driver
Display: 800 x 600 resolution
If you're on Windows RT:
Once Windows 10 starts installing, you're almost set. Depending on how new your computer is, this could take anywhere from 20 minutes to an hour or longer, but there isn't that much for you to do aside from click "Next" a few times.
CLICK NEXT, CHECK OFF SOME SETTINGS, AND YOU'RE BASICALLY GOOD TO GO
Once you're through that, the installer will finish setting things up and bring you to the desktop. From there, you're very nearly good to go. You'll want to run Windows Update one final time to make sure that you aren't missing any recent updates or drivers specific to your computer. And that's it — once you're sure everything's up to date, you're good to go: Ask Cortana a question. Stare at the beauty of the Start menu. Annotate something in Edge. And enjoy the rest of the new but familiar world that is Windows 10.