Could you add a small readme file into the dowload with installation instructions please? I haven't tried mods before and am not sure where to put the new files. Thank you.
This is the reader's digest short version... If you need more in-depth info, there are tutorials all over the forums. You'll need to modify three XML files for African units (assuming you have BTS).
1) Civ4CivilizationInfos.xml - Change African nations to use the <UnitArtStyleType>UNIT_ARTSTYLE_AFRICAN</UnitArtStyleType>
2) Civ4ArtDefines_Unit.xml - Copy and Paste entries you wish to change and point them to your own folders with these files. Copy "Maceman" for instance, and change it to "Maceman_African" pointing to your own "NIF" files that you get here.
3) Civ4UnitArtStyleTypeInfos.xml - Make an "African" art-style type (copy an existing type if need be, then only use African referances). If you look around the Civ4ArtDefines_Unit.xml, you'll notice there are already african units in the game, you just have to point them out here and you'll get a good mix of units. This part is real simple.
That's it... the above is the BEST way to do it in Civ4, but you need BTS to do it in the above way. If you don't have BTS, you'll need to make "new" units for the game for every nation (it gets more complicated and takes more effort and you'll need to change more files and it will clutter-up the Civilopedia). There's instructions for adding new units into the game, but really, you should use the BTS way for "flavour" units, rather then adding "new" units.