Once uploaded to the chipKIT board, the DAC should start playing a single note depending on the position of the frequency potentiometer (if you do not hear anything, adjust the volume potentiometer).
The sound produced from the piezoelectric buzzer won't be very loud (this is because the DAC is limited in the amount of power it can deliver to the buzzer, which is a topic best left for another project), but if it is working correctly, then turning the frequency potentiometer should change and select one of the seven frequencies available