Use the submission page and follow the instructions.
If you are defeated by conquest then submit a save from your last turn and select the pop-up option that says "The turn when I was conquered". You should have a Civ4Replay file as well. That will also be required.
If you are defeated by conquest then submit a save from your last turn and select the pop-up option that says "The turn when I was conquered". You should have a Civ4Replay file as well. That will also be required.