Watch this video: https://www.youtube.com/watch?v=nFT_Y2GAfBg for a video tutorial! :)
Before you can start the installation of Windows 7, you'd need to create a bootable USB or DVD of Windows 7.
Install the Windows 7 USB/DVD Download tool:
1. Click to open the Windows 7 USB/DVD Download tool installation file.
2. When you are prompted to either save the file to disk or run it, choose Run.
3. Once it's installed, open the program, and find your ISO file
4. The USB DVD tool will now create a bootable USB or DVD.
Step 1: Boot From the Windows 7 DVD or USB Device
To begin the Windows 7 clean install process, you'll need to boot from the Windows 7 USB or DVD if you're using a Windows 7 DVD, or boot from a USB device if your Windows 7 installation files are located on a flash drive or other external USB drive.
Tip: See my Windows Installation FAQ if you you have Windows 7 as an ISO image that you need on a flash drive or disc, or a Windows 7 DVD you need on a flash drive.
Restart your computer with the Windows 7 DVD in your optical drive, or with the properly configured Windows 7 USB flash drive plugged in.
Watch for a Press any key to boot from CD or DVD... message similar to the one shown in the screenshot above. If you're booting from a flash drive, the message may be phrased differently, like Press any key to boot from external device....
Press a key to force the computer to boot from the Windows 7 DVD or USB storage device. If you do not press a key, your computer will attempt to boot to the next device in the boot order, which is probably your hard drive. If this happens, chances are your current operating system will boot.
Step 2: Wait for Windows 7 Installation Files to Load
Step 3: Choose Language and Other Preferences
Step 4: Click the Install Now Button
Step 5: Accept the Windows 7 License Terms
Step 6: Choose the Type of Windows 7 Installation to Complete: Click on the Custom (advanced) button.
Step 7: Show the Windows 7 Advanced Drive Options
Step 8: Delete the Partition Windows is Installed On
Step 9: Delete Other Operating System Related Partitions
Step 10: Choose a Physical Location to Install Windows 7 On
Step 11: Wait While Windows 7 is Installed ( the machine will restart several times )
Step 12: Wait for Windows 7 Setup to Complete
Step 13: Enter the Windows 7 Product Key
Step 14: Your Windows 7 Clean Install is Complete!