Need assisstance replacing existing faciton symbols

Hello, I'm actually pretty new here, and I have a modding question, I haven't done any of this sort of stuff before in a success, I've tried every method.

I already have the faction symbol in its files, What files do I need to replace?
I've unified the Julii faction and renamed it to the Romans, and I got a nice banner/symbol for them, so, as the question says, what files needs replacing for both campaign and battlemap?

Thanks in advance.

I think they're all covered here.

Good luck.