Thanks for helping out...
Like I mention I've soldered all the cables from the common ground pcb to the Pi Zero W and have booted the img file by plugging in the pi to power and mini hdmi, it now says no controllers found.
I've googled around and my head is absolutely fried! I have no keyboard that would plug in, so I found that that's called a headless setup.
So to try the headless setup I put in the wpa_supplicant.conf file with the network and password, and put in a file called SSH
I booted up again and nothing comes up, even when I went on LANscan (I'm on a mac) it didn't find it

Can anyone help me get the pi on wifi so I can access it?
PLUS,
From there how do I get it to recognise the pcb as a controller, I've downloaded the retrogame.c would I be right to put that in the root (which is the /boot)
Thank you so much!