assuming you have sins 1.17/entrenchment 1.03,  the galaxy forge maps NEED to be placed here for xp
C:\Documents and Settings\'user name'\Local Settings\Application Data\Ironclad Games\Sins of a Solar Empire\

or here for vista/windows 7
C:\Users\'user name'\AppData\Local\Ironclad Games\Sins of a Solar Empire\

NOTE the first two folders after the 'user name' are hidden , so to see them you must first click on 'tools' then 'folder options', then 'view', then click on 'show hidden files & folders' then click ok, then you will be able to browse your want to the folder. I suggest when you find the folder that you create a shortcut to it on the desktop

harpo