First of all I'm NOT going to lecture you on piracy because I do it from time to time and hey, its pretty cool getting goods for free. Note though that if I do pirate something I play 1 hour worth on content as a demo and if I like it I seriously consider buying it. Now for your problem.
This is something you have needed to accept by now. You CANNOT play cracked games online. First off anyone promising you other-wise is trying to sell you something.
When you connect to a server it will register your copy of the game with it's own initial code, and when they find it's an invalid code well you're I cannot think of a SINGLE pirated game that works online, apart from very old ones. So stop being greedy and if you REALLY liked the single-player version of the game go and buy it so you can enjoy multiplayer.
I think it means you need to buy the game. MW3's multiplayer goes through Steam for matchmaking so it doesn't work without Steam.
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.