i need to create a new world space as part of the next mod i am working on. what exactly do the cell offset's do? i want my worldspace to be about as big as the capitol wasteland what do i have to do to get it that big?

I believe the cell offset fields are used to align your map image with the cells in your worldspace. It isn't used to create the actual cells. In order to create cells for your worldspace, you need to use the heightmap editor.

I've written a http://www.truancyfactory.com/tutorials/fallout_worldspace.html about setting up the worldspace data that you might want to read, but I haven't worked on it in a long time, so for further details you'll have to refer to the http://geck.gamesas.com/index.php/Heightmap_Editing.

Be forewarned that creating a worldspace as large as the wasteland is going to result in a huge file and that LOD generation is going to take a very long time.

Yea, and remember it took like 20+ people 4 years to fill in the wasteland, so if you want to completely fill yours in with things, and its just you working on it, factor in your less experienced, it will take a hell of a long time to do it. So you may want to rethink and drastically shrink the size of the exterior space, though having one is still entirely possible. Just make it like 20x20 cells max, not like 100x80ish of the wasteland.