So after about 80 hours or so into Fallout 3 I decided to start delving into the G.E.C.K a little bit to maybe start myself into the modding community rather than just the player community.
So far i'm really just in the main tutorial given on the site leading to the wiki, and after a short while it throws you into free-fall mode in which I seem to now be stumped in.

http://geck.gamesas.com/index.php/gamesas_Tutorial_Layout

If you refer to the image near the bottom of the page (first of the two large images) I am currently developing that highlighted area. As of now, the only real part i'm stuck on it the top of that highlighted area (It's above the stairs, a small horizontal room with what (I assume) are two doors) with no idea what objects those are made of.

I'v jumped through all the lists, and for some odd reason, everything seems to be to "big" in the sense, if I were to put the walls there, you'd see some of the "void" space through the little area's that didn't get covered.

I'v run through my little map over and over to make sure i'v used everything right, and everything is properly placed, but i'm stumped. So I'm wondering if anyone here can help me with this issue. I assume it's something simple, such as an object I somehow overlooked, or a small "cut this piece off" fix. However, if the latter fix is what is required, I haven't really figured out how to do that.

Thanks in advance.
I will upload my .esp file to megaupload upon request if you want/need to look at it for reference or whatever.

When I make something, I find the real game world example in a cell.

For a piece you "are" using, right-click on it in the Object Window and choose 'Use Info'. It will show all the cells that use that piece. I then go to the cells and see what other pieces are used "with" that piece. (double-click on the cell in the 'use info' list.)

Hunting and pecking through the hundreds of object pieces is not something I would do myself.

That I never knew, and thank you wholly for this information. Looks like it will help ALOT.
Unfortunately, the only "piece" i'm using that can connect to it, brings up nothing ):

Then its not used in the game. You may need to look for a different piece.
Pieces that are not used at all 'could' be bugged or not finished.

Alright thanks. I ended up fiddling with it, and decided to basically kill off the small room in the tutorial that was to the left of the vault door. So now it's just a wall.