You need to add the unit folders to Civ 3/Art/Units. You can use Gramphos' MultiTool to create a new unit in the editor for the new unit graphics. You need to be sure that the unit folder and the .ini file inside it have the exact same name that you gave it using the editor. Also, adding a new unit will cause the icons in the units_32.pcx to all shift over one space (when you look in the city build qeue, the settler icon will look like a worker, the worker will look like a scout, etc.). It sounds complicated, but after you've done it once or twice, it becomes a lot easier to understand and do.
