Hello,
To create a time difference open the toolset and create a new module. Create the area and name it Present. Don't add characters, items or placeables yet, just the basic geography. Right click on the area's name in list and select copy. Right click on this new area, select properties, and rename it future, or past or whatever. Now you have two identicle places to frame different time settings in.
Connect the the two area with an area transition trigger. See tutorials here:
http://nwvault.ign.com/modules/tutorials/viewlets/
and here:
http://nwn.bioware.com/