Install Windows 8 On Your Windows7

Download windows 8.iso from here (note: write down your  PRODUCT KEY AT THE TIME OF DOWNLOAD)

Create a Bootable USB/DVD

    

 To Create A Bootable DVD Download the .ISO and  image BURN the DVD by using NERO or any other similar application.

        

 To Create A Bootable USB Download Window8 USB Tool From Here

       

  Add the ISO file to This Tool And Make A Bootable USB

Now restart your PC. While the PC is booting up, you will have     to press a key to force the PC to      boot      from the disc before Windows loads.

Each PC vendor asks you to press a different key, but it is easy to figure out the right key for you. If you do not see a prompt on your screen during boot up directing you to a boot menu (the text-based screen described above), these are some common keys:

HP [F9], Lenovo [F12], Dell [F12], Acer [F12], ASUS [Esc] and Sony [F10].

If your vendor is not listed here, try to find the instructions on your PC before the operating system takes charge. Sometimes it disappears too quickly so you may need to restart several times to catch it.

Select your language preferences, and press Next.

Press Install Now.

Enter the product key you wrote down earlier and click Next.

Accept the licence terms

Select your partition memory ( if you don't want to change your  current OS please create a unallocated  partition by using advanced option) or select a Disc drive(eg: C or D) to fresh install

Now your Installation Still Processing

Now it’s time to personalize the Start screen. Choose a color and a name for your PC.(To keep it     simple, select the Express settings option. You can always change your settings later.)

If you have a Microsoft Live ID account, you can enter your email address here to link your PC to your account. By linking a Microsoft account to your PC, you will be able to sync your apps, files, and settings across all of your Windows 8 devices, which is cool.

 If you don’t have an account, or you don’t have an Internet connection, you can link your PC to a Live ID account later. For now, click the “Don’t want to sign in with a Microsoft account?” link at the bottom of the page.

 The PC is finalizing your settings. Congratulations! You’ve installed Windows 8.