Did he make it as a single player save or a world builder save? If he made it as a world builder save, you should put it in Documents/My Games/beyond the sword/saves/worldbuilder. Then when you start up civ4, you load it from "Custom Scenario." If he made it as a single player save, put it in Documents/My Games/beyond the sword/saves/single and just load it from the Load Game menu. (If he made it as a single player save, you need to open it with the same mod, but luckily the game will prompt you with the correct one.)
There is no way to peace. Peace is the way.