Adding the existing application on heroku and deploying on heroku

$ git remote add heroku [email protected]:name of app on heroku

$ ssh-keygen -t rsa -c "garuav[at]gmail.com" -f ~/.ssh/id_rsa_heroku

then added to my machine

$ ssh-add ~/.ssh/id_rsa_heroku

and, finally, to heroku

$ heroku keys:add ~/.ssh/id_rsa_heroku.pub

after that,

$ git push heroku master