How do I place the ~/.composer/vendor/bin directory in your PATH using .zshrc

Question

This may be a very noob question, but I'm trying to install Homestead on my Mac. I'm following installation steps via http://laravel.com/docs/4.2/homestead however there is a point in the installation process where it state "Make sure to place the ~/.composer/vendor/bin directory in your PATH so the homestead executable is found when you run the homestead command in your terminal." How do I do this using zsh? Thanks!