thanks again for all your help
Serial_MIDI says the midi message contains of 3 bytes and the first byte is seperated in an action part and a command part.
so i first tried sending 3 bytes
Serial.write(B00000100);
Serial.write(B00000100);
Serial.write(B00000100);
(the prefix B should also work right? Integer Constants - Arduino Reference)
and i tried splitting the action part and command part
Serial.write(B0010);
Serial.write(B0010);
Serial.write(B00000100);
Serial.write(B00000100);
but in the conversion software the light still turns red (which means it is reading serial data but it's not midi format.