It isn't a silly question at all, I think everybody thinks the same thing first time around. And whether you're fourteen or fortry, becoming a Mother is a daunting and scary thing.
I agree with many of the sentiments here. Nobody can really explain it to you, it just happens. But you can prepare yourself by getting as much knowledge, with many helpful books. You could go down to your library, and check out several. As I admit I've spent money on certain books that I wished I hadn't.
You say you know how to feed -- are you planning breast or aritificial?
I don't want to go through a common misconception here, but are you with the Father, and is he pleased?
You have many weeks ahead of yourself before he/she arrives, it'll seem like a lifetime.... Take good care of yourself.

xxx