Thanks for the warm welcome, Cap'ns...
Please note I'm a total noob, both to the game and modding, but as retired graphic pro, I JUST COULD NOT STAND how my monitor (21:9 aspect) would interpret the range rings of a certain Mod... so a little poking around and a few PNGs later I am HOOKED. I'm not a programmer, so I've got a lot of learning to do, and my focus is for now on just layout/splash screens, but I still don't know how/where files are to replace them.