What Andrew said. start at the beginning. And this question isn't even AE specific in the first place. Before thinking how to multiply stuff, you need to think about how to shoot it in order to be able to do it at all...
i am also very new to AE, but have been going through some tutorials etc for the past week or two. try this site out:
it was suggested to me by some of the people in the forum, and it is absolutely crammed with good info, and basic tutorials. spend some time on the link to Andrew Devis' Basics tutorials - it is Gold!
Hope that help, and as one beginner to another - Good Luck! :-)