Intel Galileo Hardware Manual page 21

Hardware
Serial.print(readValue); //output the read value
Serial.print("\t"); //put a tab between the values to make it
easier to read
Serial.print(writtenValue); //output the written value
Serial.print("\n"); //Write a new line
analogWrite(3, writtenValue); //write to the led
delay(100); //delay a bit
}
The program is a lot longer, but it gives nicely formatted data to the serial monitor.
And finally, this is what your musical instrument might look like (Lesson 3, Figure 6):
Lesson 3, Figure 6
Hardware 21