Ooh yay you installed my custom image! I’m guessing you installed the latest 200224 build? Don’t forget to run the file system expand script located in the utilities folder to use all the available space on your SD card. This image doesn’t automatically expand. Yet ;).
I’m glad you mentioned this, so I can reference the correct file directory structure.
You’ll need to type:
scp “source of the file on your computer” “destination of where you want to put the file”
Eg,
scp game.iso cpi@192.168.0.10:games/PSX/There are a bunch of other options you can add to the process. You don’t need to worry about them for the most part, just doing a file copy.
check this out
This is assuming you know how to connect to your gameshell via SSH. Hopefully you’ve gotten that. There are a few tutorials on how to do that in the forums.
ssh tutorial
That said, I have a feeling you’re having a problem with file format compatibility. Sending it via ssh would be no different to using a GUI like FileZilla, unless it’s configured incorrectly, or if windows hasn’t added it to its firewall exception list. I haven’t used windows in years, so can’t say how security etc behaves these days. Not have I ever used FileZilla. I used to use putty back when I used windows more than a decade ago.
Sometimes when you download an image, it might be in a compressed archive, like a *.zip file. You’ll need to decompress it. Sometimes it’s in a PSP eboot format, which will need to be converted first. If you can just take a screen shot of the file you’re trying to send, we’ll be able to identify if it’s compatible.
There’s something called an action.config file. It’s what tells the pcsx directory what kind of file extensions to show in its list. In a nutshell, your file type needs to be one that is referenced in this action.config file. You shouldn’t need to modify the action.config file, as it has the most common file types listed by default. You could possibly be using a game that isn’t a common format.
Finally, you might need a bios file. This needs to be in the correct format, and placed in the correct directory. We’ll cross that hurdle once we work out what game your using, and it’s exact file extension/format.
Have you gotten anything else to work on the Gameshell? Like, have you had any luck transferring any other console Roms? Just trying to gauge where you’re at.
Let me know how you go! 
We will get PSX games working!