I've had swine flu all fall break (it sucks and it's only getting worse)

My parents told me there's been about 5 deaths here from it and it's because when it turns into pneumonia, that's when it gets deadly.

I know swine is just as deadly as the regular flu, but how does it lead to pneumonia or cause it? They told me to be careful and try to stay healthy but how am I supposed to if I don't know what I'm trying to prevent? :/