Windows system commands in gamemaker. How to?

I have downloaded this extension from the marketplace: https://marketplace.gamemaker.io/assets/1481/windows-system-commands
but since I'm not that familiar with coding, I just started to with gamemaker. The extension doesn't do what it's saying to do, and I don't know if the problem is from me or the extension, can anyone tell me what they would do for the SystemCMD() command to work?

Thanks a lot~