Hello. This is my first time using any Arduino board. I've been trying to upload my sketch into an Arduino Uno, but the only serial ports available are /dev/cu.Bluetooth-Incoming-Port and /dev/cu.Bluetooth-Modem. I checked this website, which said, for a Mac, there should be a serial port called /dev/tty.usbmodem621 or something like that in the case of the Uno. The OS for the mac is 10.10.5. Sorry 
, I'm brand new to all of this.
Thanks.