Get a USB drive with at least 8 GB of space
Back up any files on the USB drive
Download the Windows ISO from Microsoft
Download and open Rufus
Insert the USB drive
Select the USB drive in Rufus
Select the Windows ISO file in Rufus
Choose the correct partition scheme and target system
Click Start
Wait for the process to finish
Safely eject the USB drive
Boot the target PC from the USB drive
Follow the Windows setup steps