Can you explain the basic rules of american football?

My dad is a huge football fan (Dallas Cowboys), but I've never been into it much. I'll be honest, I prefer soccer. Anyway, I want to be able, come football season (yes I know it's early)\ to sit through a game with my dad, and understand what's going on. I just don't want him to think I don't care about his interests. So, if you could explain some of the basic rules, or whatever, it would be really appreciated. For instance, what is a touchdown, a yard, a down, a...scrimaj? I don't know how to spell that, and yahoo isn't helping.