What are the addresses to....?

I'm 13 yr old girl and im going to write at least 2-3 letters to big corp. all around the world. But I need their addresses and some suggestions. My first one is Hershey, Pennsylvania. You know where they make all the choclate. whats their address ? also I need some other suggesstions kinda like places where they would write/reply back or some animal funding place. where i could write 2 important people about what they need to do to stop whaling, global warming, stuff like that. thanx. oh remember im only 13 so no where bad cuz my parents have 2 read the mail i get. also if u could put an email where i can email them to that would be great ! thnx