I have downloaded the iso file of Windows 10 installation disk from https://www.microsoft.com/en-us/software-download/windows10ISO . But I do not have a DVD R/W drive. Whether and how to install Windows from a USB drive?
You can use the Windows USB/DVD Download Tool to make a USB from the Windows ISO.
Download and install the Windows USB/DVD Download Tool from http://wudt.codeplex.com/ .
You can follow the wizard of that software to make the USB drive from the Windows ISO file to install Windows.