Adding Units to Civ4

[N8DoGG]

After playing through the game once I figured out what units I thought the game needed, and then to work finding and downloading them, as I did with civilization 3 when it came out. but unlike civilization 3 I can't seem to find a thread that describes the procedures of adding units in a way I can figure out. I've seen tons of posts with titles like "adding new units" but the directions are obscure and I can't seem to follow them correctly. Will someone please make one complete thread about how to add units and all the associated files? And do i need to download a program to help myself in thios great endeavor??

Thanks and sorry for beeing such a noob...