Change baud rate

Hi,
I use an Arduino Nano on Win8 and I can't successfully a program.After endlessly searching through forums one of my professors suggested to me that I might have a problem with my baud rate.
He told me to change the baud rate to 19200.

After looking it up on the internet I figured that I have to change the baud rate in the serial monitor and upload a program with "Serial.begin(19200);".

However when I press upload, the verbose output says Overriding Baud Rate : 57600

Did I do something wrong?

Probably just misunderstanding. Overriding Baud Rate message is related to sketch uploading procedure. Baud rate in this case depends on bootloader setting, in the boards.txt is the upload speed. It has nothing with the sketch and baud rate used in your program.