In the game folder, find the Civ4Config file and
Cheat Codes for Civilization 4 Free Download
open it with any text editor:
Find the line:
CheatCode = 0
and change it to
CheatCode = chipotle
Bo while playing, press the [~] (tilde).
Then enter help and you will see a list of all the available cheat commands.
Example of entering a command:
Player.setGold 0 100000