Here is what I did on my Mac to get echo setup. (with some other possible steps thrown in)
If you don't already have a GitHub account, the first thing you'll want to do is go to github.com and sign up.
go to https://github.com/echosystem/echo, then click the "fork" button towards the top right to get your own private copy of the code.
Make a git clone of the repository on your computer. You want to use the private clone url, which should be git@github.com:username/echo.git
If you don't already have git, install it. On mac I use Homebrew to install by running
$ brew install git
but there's also downloads at http://git-scm.com/
Once you have git installed, you should be able to run
$ git clone git@github.com:username/echo.git
and it will create a directory within the directory from which you ran that where all of echo's files will be.
Once it's cloned, cd into it.
$ cd echo
MySQL is a popular database that echo uses.
I installed it with homebrew.
$ brew install mysql
Also installers here
You need Ruby and Rubygems. Mac ships with both, so I didn't do anything. http://www.ruby-lang.org/en/ has downloads.
I took the gems listed on the pirate pad and made a list of gem install calls to match. Download the file, which is at https://gist.github.com/raw/1361003/7f888cab83b652741de7fc1969d6bceb92e1e02f/gems
and then from that directory run
$ sh gems
You should see a lot of gem output. If you see one or two failures it's quite possible that things will still work, so make note of which had problems but try moving on.
Download this file https://gist.github.com/raw/1361003/65383b4eb234f863fcd31d47949387fd6f551ef8/database.yml
and put it in the config/ directory of echo.
Note that this assumes that your "root" (administrator) mysql user has no password. This is the default. It's also pretty bad practice, and it's pretty bad practice to actually have an application use the root user. But if you just installed mysql, you don't have any other databases for it to potentially mess up, so it's safe. If you already had mysql installed and have other databases, even though Rails doesn't do anything stupid and only touches the database you tell it to touch, I'd recommend setting up another user with a password and changing the user line in database.yml to that username, and also adding a "password: whatever_the_password_is" line.
Once your database.yml file is in config, you can create and setup the database by running:
$ rake db:create # make the database for echo
$ rake db:reset # create all the tables
$ rake db:fixtures:load # populate it with some initial data
Now everything should be ready to run echo. run
$ ./script/server
Wait a few seconds and then go to http://localhost:3000 in your browser. Hopefully, you see echo.