If you mean worldMAP
You need to change map pic first, put new map pic in client\data\art\interface\yourmap.png, changew name of map in \data\art\interface\default.ini
if you are using one big picture:
GmapTilesPic = yourmap.png #
GmapTilesX = 1 # Number of pics width
GmapTilesY = 1 # Number of pics height
in config.fos:
__GlobalMapWidth = 28;// Number of squares
__GlobalMapHeight = 30; // Number of squares
__GlobalMapZoneLength = 50; // sqares widht and height in px
worldmap.fos:
#define ZONE_COUNT_X (28)
#define ZONE_COUNT_Y (30)
#define ZONE_LENGTH (50)
at the end of this file you must find line
LoadImage( IMAGE_RELIEF, "relief_tla.png", 1, PT_SERVER_MAPS );
it means relief file - Server\maps\relief_tla.png
Then change coordinates of towns:
Server\maps\GenerateWorld.cfg
If you mean townmaps just use MApper and edit maps*)