Real Time Plotting Tool ( Oscilloscope )

as i type this out i realise it's most probably a massive noob question , but i still hope u can help im running and Arduino UNO and im trying to run your sample code for four analogue outputs to sim plot . im confused about where i get the imformation to fill out this line in your code ??

im using com port 10 if that help's any help would be great

//IMPORTANT: Change to serial port that is connected to PC
  Serial.write((uint8_t *10 )buffer, pktSize);