What do I need to know about football?

Ok, so basically I know nothing about football except that people tackle other people. I've never watched a football game in my life. Never played a football game in my life. But tomorrow is the Super Bowl, and now for some reason I actually want to see it. So what I'm asking is, what do I need to know? Players, positions, etc. I just need to know basically who they are (Steelers and Packers) and how to play, and who plays what? Thanks!!!