If you aren't familiar with join statements then that is where you need to start. Understanding how joins work is key to the rest. Once your familiar with joins then understanding the merge is easiest by thinking of it as a full join with instructions on what to do for rows that do or do not match.
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.