How to use Civ3Edit
If you are interested in creating a map, and do not wish to alter the way the game plays, simply select a brush and begin "painting" your world on the map window. For a brief synopsis of using the map editor, see "How to Create a Map".
If you wish to edit game rules without creating a map, you will need to check "Custom Rules" on the Tools menu to enable rules editing. Make sure you do not check "Custom Map", or the editor will assume your scenario file contains a map and will save that potentially blank map with your scenario.
For more details on rules editing, see "How to Edit Civ III rules" , or the index of rules property pages.