You need to install the library : in the Arduino IDE, go to sketch > include a library > manage library, it opens a new window where you can search for a library. Search for "JC" or "JC_Button", and click 'info' then 'install' (I hope it works like this in the English version of the IDE).
Then compile and test.Enjoy and tell me if it works ! If yes, you can delete the commented lines.
Yes it works great, thanks again,