The actual width and height (resolution) of these pictures on my monitors is 5760 by 1080. All you'll be able to get is an impression of what it looks like. That's why I usually post most screen shots in "dual screen".
Prepar3d could do more to make the multi monitor flight simulation better, but it's better & simpler now than it is for FSX. That's not to say that you can't get similar results with FSX. You just may have to go through a few extra steps.
In the first screen (somewhere in Cumbria, UK) all of the icons are hidden. This is just to make the desktop look less cluttered.
One thing nice about P3d is that it'll open in the same position that it was when you last quit.
If you have it spread across two or more screens, and then hit the "ALT" and ENTER keys together, it'll fill up any screen that it partially occupies.
In this case Prepar3d bridges all three screens, so when I hit "ALT" and ENTER it fills up the entire set of screens and hides the menu & windows borders.
Makes the cockpit more enjoyable too.
A few notes
1 - When in full screen, you can toggle the menu on and off with the "ALT" key. The window boarders will stay hidden.
2 - When in full screen, you can exit by hitting the "ESC" key and choosing to exit. The next time that Preper3d opens it will fill all three screens, and, of course, without borders.
3 - Enjoy your flights.