Trading with Fibonacci retracement

Hi guys. Can you share here please how do you use fibonacci retracement levels in your trading and do you find it as a valuable tool or not?

I have read this article, which claims that Fibonacci levels are human made, but I don't understand the technics used in it to be honest

http://ift.tt/22rs3Hv

Any advice or opinion is much appreciated!

Trading with Fibonacci retracement