2- Install the Heroku toolbelt. Google it yourself!...
3- Open a terminal, and to login to heroku
<code>
#> heroku login
</code>
4- Generate you key
<code>
#> ssh-keygen -t rsa
</code>
5- Add the key to your heroku
<code>
heroku keys:add
</code>
6- Clone your existing repo.
<code>
git clone git@heroku.com:<YOUR-APPNAME>.git
</code>