iLelouch:
sry, i mean.. i have to make a serial communikation (rs232 ) between a computer and the arduino ide (seriell monitor), i got this task from my teacher idk what to do
Perhaps you teacher just means to make a serial connection to the IDE. RS-232 cannot be done because the IDE uses the USB connection. Writing a program to send and receive from the IDE serial monitor would be a good first exercise.
Paul