There are two aspects to the eChook code - the code itself, and any code libraries that the main code references. The eChook code is dependant on one library called ‘Bounce2’ which is used to debounce the switch inputs.
Download the Bounce2 library from here:
Now back in the Arduino IDE go to Sketches>Include Library> Add .ZIP and select the file you have just downloaded.
The message bar at the bottom will confirm the library has been added:
Just like the library just installed, the eChook code is hosted on github here. Download it and extract it to a suitable working directory, eg. …\My Documents\eChook.