This is why you didn't understand my first questions..
So.. Hairless-midiserial let you communicate Arduino with PC through the messages it sends to serial monitor.. When you open hairless you have to choose the right source for the Arduino messages... You have to syncronize the reading by putting the same rate speed for serial and hairless... But you have to send to serial a precise code which is a MIDI code.. Now.. My question is: which is this right MIDI code to control knobs and other software elements? How can I send this message as MIDI message to serial monitor? What is the right code?