Newbie Arduino connection help

Hi all!
I am new to Arduino and I have just got Arduino UNO R3, and when I'm trying to find the board on the serial port, it doesn't come up. I have tried Youtube videos, but none of them have worked.

I was trying to upload "Blink" from the sample file, but it says:

avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding

Is there anything that I have missed during installation?
My operating system is a Mac Mojave.
Thanks for any tips and suggestions!

Cheers
Al

What is the USB to TTL serial chip on your Uno? It will be written on the larger black chip nearest to the USB jack on the board. It will probably say either "MEGA16U2" or "CH340".

Thanks for replying! The black chip on the UNO board says "MEGA16U2"