Well, you will have to buy it. Honestly, I would stick with Windows 8, it's much faster.
You will have to find and purchase a full copy of windows 7. And then you will need to backup your pc's files and programs to and external hd. Next go to your pc's OEM website (Dell, HP) and download all drivers for your pc for windows 7.
Then you will need to do a complete full install of windows 7 meaning it will erase everything on the pc.
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.