To add a Heroku app as a Git remote, you need to execute heroku git:remote -a yourapp.
Here is a proper demonstration:
Initialize GIT
$ cd myapp $ git init $ git add . $ git commit -m "my first commit"
Then create (initialize) heroku app with:
$ heroku create YourAppName
Lastly, add git remote:
$ heroku git:remote -a YourAppName
Now you can safely deploy your app with:
$ git push heroku master
You should wait for some time and see if you don't get any error/interrupt on console while deploying. For details look at heroku article.