I really need to write it up properly!
You don’t need to do any coding. You can just use the emonSD image and edit emonhub to read the data and send it to your main base station. In theory you can just install emonhub, but let’s keep it simple!
If you add the 5th wire (rst), if you need or want to update the firmware on the emonTX it is very easy to do, but you probably don’t have to. Ignore this for now.
Have you any jumper wires?
Paul has a good diagram of the wiring here 4 CT emonBase using emonTx and Pi Zero W - #17 by pb66. Ground on the emonTX is the right most pin.
Remember, you are powering the Pi from the emonTX so do not put power on the Pi as you normally would.
Once wired, fire up an SD image, I would add a wpa_supplicant file - much easier to setup Wi-Fi that way and remember to leave it for a while to update. Then we can look at the serial interface.
miniterm /dev/ttyAMA0 115200
and hit the reset button on the emonTX. (EmonTX to Rpi - Direct Serial Connection - #47 by borpin)
If you get this far you are well on the road.