There are several operating systems, however must of them are under Windows. Starting from old to new, there is Windows CE, Windows 3. X (series included 3.0, 3.1 , 3.11 and so on), Windows 95, 98, 98 SE, Windows ME, Windows NT, Windows 2000, Windows XP, Vista and 7.
There is also Linux and the different versions, MAC Operating system, MS-DOS, IBM OS/2 Warp and Unix with different versions. Most home PC use some version of Windows, unless it is a Mac. You can find more information here: http://www.computerhope.com/os.htm.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.