and it works very fine
How do you know that ?
Did you get that openSource project running? Congratulations !
I don't know much about mC Programming
Did you try to run an Arduino button sample ?
Did you understand it ?
A working project is a valid starting point to learn, if you do not prefer to start from scratch and easier samples.
To understand Stefan Brenner's code : the Arduino part seems pretty simple:
void loop() { // nothing to do here}
My hint: here's where any button code goes. Probably you are able to trigger a valid ProcessCommand("whatever goes here");