How do I get USB to UART working

I have just received the USB to UART seriel console cable, and is seen in my ubuntu laptop as pl2303 converter now attached.
Then it says pl2303 converter now attached to ttyUSB0

How do I get the pi 3 desktop after connecting the Red to 5V, Black to GND White to BCM 14 and Green to BCM 15. Are these connections correct or on the wrong pins.

Make sure you have enable_uart=1 at the bottom of /boot/config.txt on your Pi.

You will not get a desktop- Serial/UART is for a terminal/command-line session only.

If you’re using a Linux host you can then open a terminal and type something like screen /dev/ttyUSB0 115200 to open a serial connection to your Pi at 115200 baud.

If if appears to connect and you see nothing, hit a few keys, or enter a couple of times.

Ah, ok thanks.
Is it something like SSH,which I use quite often.

Actually it is already there as I used raspi-config and enabled it there

I have had a go with using this link:

And when I run this: sudo screen /dev/ttyUSB0 115200, I get a blank screen with a flashing cursor.

It does much look like SSH??

Absolutely! The humble serial port was the defacto standard for getting at a terminal on your hardware. SSH is just a complicated and secure way of doing the same thing over a network.

If you connect to the serial terminal before booting your Pi, you’ll see the boot process too. This is handy for debugging.

Hang on a sec, does the pi3 need it’s normal connection lead /micro usb plug as well as the connection with or from the USB to UART, as I am only using the cable connection now.
Plugging in the normal psu to the pi, and nothing happens as the cable is still pugged into it and usb on my laptop

The Pi 3- probably, yes. USB is technically only rated for 500mA although in practise you can draw more from some ports. The Pi 3 needs at least 1A IIRC.

I have run other Pi’s entirely from the UART cable, but your mileage will vary depending on how forgiving the ports on your computer are.

The USB to UART connection is drawing between 0.28 A to 0.64 A when plugged in to the usb port on both laptop and desktop.

All in all it doesn’t do what I thought it would do, and doesn’t look like it will.
I’ll ask if I can return it on Monday