I tried to install composer via brew per:
brew tap josegonzalez/homebrew-php
brew install josegonzalez/php/composer
php composer.phar install
Composer could not find a composer.json file in /usr/local/bin
To initialize a project, please create a composer.json file as described in the http://getcomposer.org/ "Getting Started" section
The "Getting Started" page is, as you obviously didn't notice, the introduction to the documentation. Most documentation will start off with installation instructions, just like Composer's do.
The page that contains information on the
composer.json file is located here - under "Basic Usage", the second page.
I'd recommend reading over the documentation in full, so that you gain a better understanding of how to use Composer. I'd also recommend removing what you have and following the installation instructions provided in the documentation.