This is even a better site to see in detail how to set your path in Windows 10.
Add to the PATH on Windows 10
https://www.architectryan.com/2018/03/17/add-to-the-path-on-windows-10/And if you are using Microsoft Visual Studio to get a C compiler for the NASM .obj files, and want to use their fairly new Powershell command tool rather than the DOS Visual Studio command prompt, you may want to add the directory where their cl.exe is located. Actually there four directories, depending if it is x64 or x86 AND Hostx64 or Hostx86. Quite a maze to navigate the path but using Powershell with it's BASH style command in addition to DOS is a lot better for me. And if truth be known, I have had a lot better luck running NASM on Linux than with Windows.