Serial.begin(9600) print window

I am trying to do this simple code but nothing happens. I mean, It should open another window showing the words "Hellow world", right?

void setup(){

void loop(){
  Serial.println("Hello world");

Yes you should open the serial monitor. This can be done from the IDE in the TOOLS menu -> Serial monitor

Note there is a baud rate (speed of the chars coming in) in the lower right corner

Hmmm. Thank you very much! I am beginning (=

You will learn all the things eventually, just go one step at the time, do not try to do too much at once.

Have you been on the tutorial section already?

I no, I haven't. I olny saw some good videos at youtube. I will try it!!