youtube-dl not working

I'm running Win 10 64 bitn it I have Python 3.6 installed

I have downloaded youtube-dl and whenever I try to run it in Powershell, I get this message:

"youtube-dl : The term 'youtube-dl' is not recognized as the name of a cmdlet, function, script file, or operable program."

I've tried to run it in command prompt too and it won't work either.

I've downloaded win-youtube-dl.exe and nothing happens. The cursor gets a busy indicator for a second then nothing.

I'm sooo frustrated, please help!