how to get a flag/coat of arms into the game

[Pellaken]

I have a PNG file that I want to use as a flag/coat of arms, but cant figure out how to get it into the game. I've tried looking it up but it's giving me super complex things about per fess something; all I want is my entire image to be the entire coat of arms / flag. how exactly would I do this?

 

[Pellaken]

can anybody help at all?

https://i.imgur.com/qEHd8SC.png

this is the image I want to put into the game as as dynasty flag, and maybe if I can work it, also as the flag of my "country"

ideally I'd like to add a few more things - this is all technically "fanart" as I said as an aside I should make a strategy game based on the community before realizing I could actually pull that off just by modding the people into a strategy game - IE CK2.

If I can't do this in CK2 I'll have to find another game to mod them into the problem is the ones with easily editable art (EU4) lack a lot of characters to play around with (Generals don't have pictures, Advisors don't have stats) and non-paradox games with easily editable characters (RTK13) don't have art I can play with.