I have search on many forums which adressed to similar problems as mine: how to put the libraries "CapacitiveSensor" to work, but none has helped me.
I downloaded it and put it on the folder Arduino->Sketch->libraries , having created this folder like they told to do on page 137 of the Starter kit book.
In my preferences for Sketchbook location I have ... /home/username/Documents/Ardunio (check yours)
thus the Arduino library directory is
/home/username/Documents/Ardunio/libraries
If I unzip the d/l file into my Arduino library directory, the zip directory structure is appended to the arduino libray directory, thus creating the following ...