[continued] how do I change the GRUB background image?

Here is the answer from the Libreboot chat.

> A: you need to get familiar with CBFS. "yourrom" means "your rom" = what you have installed
installed = flashed

> ME: *kindly askes for further details / explanations*

> B: just leave it be if you're not willing to do your own research, "A" pointed you in the right direction.

> A: "yourrom" means "your rom" = what you have installed

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Then there were some further comments that fall under "trolling" in my book, but maybe I am wrong and the answer is hidden somewhere between the line:
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> A: you could also say that by installing something, you "put it in" to the box you call a computer. If you put something in, and the box did not belong to a quantum physicist, you can usually take it out again.

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Seems, the Libreboot community doesn't really help here. So I repeat my question I posted in that (kind of hostile) chat:

I'd like to change my boot background image. I found a thread in the trisquell forum saying "cbfstool yourrom.rom ..." does the trick. Alas, I don' know where to find yourrom.rom. Any pros around who can explain this to ppl that aren't familiar with the whole Libreboot matter?

Hi AyKay, what the users in the chat are trying to explain is that you are not looking for a file called "yourrom.rom", there is no such thing. Rather, it seems that "yourrom.rom" is a description of a thing you need to know the name of.

This is like if I told you to run a command that addressed /dev/sdx. You will not find sdx in the /dev folder, it does not exist. Rather, /dev/sdx is a way of telling you where in the command to put in the address of the drive or partition you want to be the target of that command. Does this make things clearer?

Sadly, I have not yet librebooted my laptop, so I can't advise you in any more details on how to find out what you need to put in place of "yourrom.rom" in that command. Others here can probably help?

Thanks @strypey !

Yes, I figured this myself (during that chat), that yourrom.rom is actually a handler pointing to the "rom" in place (means the one flashed onto the system). If this is true, the commands can be used with "yourrom.rom" straight away. But I read several times (in the libreboot docs) that you ought to replace "yourrom.rom" with the appropriate rom you pick from a repos. (Maybe just during inital setup!?) So it's not 100% clear. (Alas the 160 ppl in the chat totally failed to give a clarification here; my gut feeling is the answers is pretty simple.)

I keep on searching and will post the answer later.

cheers!