Newbie question about including static leaderheads

[Martinus]

I tried finding an answer for this in the tutorial forum, but couldn't so asking here.

I have some leaderheads I would like to include for the Polish civ, done in the dds format (both normal leaderheads and buttons). I checked how civarmy, Lankou and others included theirs and tried doing the same, but just got pink empty squares in game where the leader portrait should go.

Additionally, I have seen they also modified the "atlas" files - what is the purpose of those and how do I go about it?

Any help would be welcome.

 

[Martinus]

*bumping up*