EDIT: I think i am now answering your question here -> You MUST save your map to the correct place... \Sid Meiers Civilization IV\PublicMaps\ .... otherwise it cannot be reopened in my experience. It is then a scenario available for opening.Hope that helps.If not, then read below!
Im not quite sure if i am answering your question here but here goes:
Im presuming you mean you want to edit the variables such as StartYear, etc?
Firstly, make sure you have saved your map to PublicMaps folder. Then exit the game and browse to <Install Directory>\Sid Meiers Civilization IV\PublicMaps\ and right click on your Scenario/map name. Click 'open with...' and select the most powerful tool known to man- Notepad.
Then do what you will, e.g change the following:
- Era=: The Era setting is used to determine what era the scenario begins in.
This setting helps determine initial graphics sets used for cities, and the
music score. Depending on the period of history of your scenario
determines what setting you would use here. EG: If the scenario is based
in the 1940’s you would set Era=ERA_MODERN.
- Speed=: The Speed setting is used to determine the scenario’s timeframe,
and speed at which development is to progress. By default the speed is set
to normal. Available options are GAMESPEED_FAST,
GAMESPEED_NORMAL and GAMESPEED_EPIC. These represent
the same settings as you would choose from the pre-launch setup screen.
- Calendar=: The Calendar setting is used to determine the length in time of
each turn in the scenario. By default the calendar is set to default which
means the scenario will use the same turn length time as the normal game.
Valid options include CALENDAR_YEARS (each turn is one year),
CALENDAR_SEASONS (each turn is one season: Winter, Spring,
Summer, Autumn), CALENDAR_MONTHS (each turn is one month)
and CALENDAR_WEEKS (each turn is one week, with four weeks to the
month).
- Victory=: The Victory settings are used to allow victory conditions in the
game. By default all victory conditions will be available. By simply deleting
the entire line of any victory condition you do not want will stop that
condition being possible in the scenario.
- GameTurn=: The GameTurn setting is where you can set what turn the
scenario will start on in regards to the Calendar and StartYear settings. By
default the GameTurn will be zero (0) which means the scenario will start
at the beginning of the calendar. If you wish to start the scenario part way
through the calendar then you set the GameTurn to the relevant turn
required. EG: The scenario you designed must start in July. You set
CALENDAR_MONTHS but the scenario will start in January. By setting
GameTurn=6 (0 = January, 6 = July, 11 = December) then you can force
the scenario to begin in July.
- MaxTurns=: The MaxTurns setting determines how many turns the
scenario will play. At the end of the turn specified by MaxTurns the score
victory condition is triggered and the scenario is ended. You may set any
value you wish here, but obviously it would be illogical to have the
MaxTurns less than the beginning GameTurn.
- MaxCityElimination=: The MaxCityElimination is a good setting for
multi-player scenarios. This setting will over-ride the multi-player prelaunch
setting of how many cities you may lose before you are eliminated
in City Elimination games.
- TargetScore=: The TargetScore setting is useful when your scenario has
objectives to be met (see the Civilization IV “Desert War” scenario where
you have 6 objective cities on the map). Once a player’s or team’s score
has reached the required TargetScore they are declared the winner.
- StartYear=: The StartYear setting allows you to force what year the
scenario will begin in. To set a BC date you simple use a negative number.
EG: -3500 = 3500BC. Keep in mind the StartYear, Calendar and Era all
tie into each other to form the correct timeline for you scenario.
- Description=: The Description setting allows you to display a small
amount of descriptive text in the scenario selection window. You can use
this description to give a brief outline of what the scenario is about.
- ModPath=: The ModPath setting is only used when your scenario is part
of a larger Mod. If you have xml file modifications, python scripts or
graphic changes then your WBS will be part of a full Mod. These are
stored under the Mods folder.
This information was taken from the "Civ 4 Modding manual PDF" which is available on this very site, written by Dale. In my opinion well worth a download.