Upgrading my version of Rails?

Hi, I realize this may seem like an easy question, but I'm kind of
stumped. I want to upgrade my version of Rails from 1.0.0 to 1.1.6. I
downloaded rails-1.1.6.zip from rubyonrails.com, and I don't know what
to do next. Where should I extract it, and what should I do in the
console to install it? I'm on Mac OSX v. 10.4.8, Intel.

Open Terminal.app (or whatever shell program you favor) and type

  sudo gem update rails --include-dependencies

Best,

-r