Summarize this article:

The most recent version of Windows 8 is Windows 8.1, which is the only version of Windows 8 on the Microsoft Website. You can find versions of Windows 8 Pro on Amazon and in some tech stores. If you already have a CD version of Windows 8, skip this step. . Since you'll be replacing whatever operating system and files you currently have with Windows 8, make sure that you have a backup copy of everything that you want to keep before you proceed. The CD should go logo side-up. If your computer doesn't have a CD slot, you'll need to buy a USB CD reader and attach it to your computer. Open Start {"smallUrl":"https:\/\/www.wikihow.com\/images\/0\/07\/Windowsstart.png","bigUrl":"\/images\/thumb\/0\/07\/Windowsstart.png\/30px-Windowsstart.png","smallWidth":460,"smallHeight":460,"bigWidth":"30","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of a Windows icon.\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Public_domain\">Public Domain<\/a><br>\n<\/p><\/div>"}, click Power {"smallUrl":"https:\/\/www.wikihow.com\/images\/5\/5d\/Windowspower.png","bigUrl":"\/images\/thumb\/5\/5d\/Windowspower.png\/30px-Windowspower.png","smallWidth":460,"smallHeight":460,"bigWidth":"30","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of a Windows icon.\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Public_domain\">Public Domain<\/a><br>\n<\/p><\/div>"}, and click Restart in the pop-up menu. Your computer will begin to restart. This key is usually either an F key (e.g., F2), the Esc key, or the Del key. You'll need to do so immediately after the screen goes black.  The key that you're supposed to press may briefly be listed at the bottom of the screen. You can check your computer's manual or online documentation to see which key opens the BIOS. If you see the startup screen, you'll need to restart the computer and try again. On most computers, you'll use the arrow keys to select the "Advanced" or "Boot" tab to do this. Some BIOS models have the boot order options on the initial page on which you arrive. It should be labeled "CD Drive" or "Disk Drive" (or something similar). Again, use the arrow keys to select the appropriate option. If you're using a USB CD drive, you may instead have to select "Removable Storage" (or similar) here. Make sure that you don't have any other USB items (e.g., a flash drive) plugged in if you do this. With the "CD Drive" (or similar) option selected, press the + key until the selected option is at the top of the boot list. If this doesn't work, check the key legend on the right side (or bottom) of the screen to see which key you should press to move the selected option. For most BIOS pages, you'll press a key to do this; check the on-screen key legend to see which key you need to press. Once you've saved and exited, your computer should begin booting into Windows 8.
Buy an old version of Windows 8. Back up your computer's files Insert the Windows 8 CD into your computer. Restart your computer. Begin rapidly pressing the BIOS key. Find the "Boot Order" section. Select your computer's CD drive. Move the drive to the top of the boot list. Save and exit.