This wizard will help you create a multiplayer scenario for Battle for Wesnoth.
First, create the map in game editor.
In Start menu select Wesnoth | Map Editor.
Paint a map using the terrain palette.
Set starting positions for all players (min 2, max 10).
Save the map in directory C:\Program Files\Wesnoth\userdata\editor\maps\ under unique name,
for example my_map.
Now you can start Battle for Wesnoth, click Multiplayer and select this map in menu.
If this is all you want, you do not need this wizard.
This wizard can help you set more details to the map (though not very much in version 0.1).
Click the buttons at the top of page to go through the wizard pages.
Fill in the values.
At the last page, a "scenario script" will be generated based on provided values.