[Chadmando]

Hi, I have just installed XBMUBUNTU on my HDD. (Please, treat me like a 5 year old that doesn't know what their doing).
Having problems from the start... the XMBC will not detect my second display, when trying to set my display the only option I get is "Fullscreen #1 and Windowed mode does nothing/ doesn't work (reverts back to fullscreen#1).
Initially I couldn't get to the ubuntu login screen, I booted to the"advanced mode" and I now can.
Anyway the Ubuntu "OS?" recognizes both monitors and I had dual monitors going.
I started playing around with the display settings (preference->Monitor Settings) I unchecked and then rechecked the option to turn on/off my second display now and now I just get a mirror of my main display.
Now XMBC still doesn't detect two seperate monitors but plays the image on both monitors (completely undesirable).
What do I do
I need step by step please do not skip steps.
Help would be greatly appreciated.

EDIT: UPDATE
Ok So I figured up how to pull up the dos thingy and how to switch between that and the OS thingy lol.
I've somehow managed to get it so I've got the normal two displays again (Like I move my mouse further and then it gets to the next screen). Now when I load up the XBMC boot I can switch to window mode and see the two displays, What I still can't do is go full screen on the display I want. XBMC still only reconigzes one display.
I should add I am using a Nvidia graphics card.

[Ned Scott]

In XBMC go to

Settings -> System -> Video output

And change video mode to screen #2.

[Chadmando]

That doesn't work it won't give me the option of screen #2. Just fullscreen #1 and windowed mode. I have the windows version and it works fine in Windows.