Process for deploying app on heroku :-

1) sudo gem install heroku
2) heroku create app_name
3) git init
4) git add ( add the files present in the app, see the files by ls command)
5) git commit -m "commit the app"
6) cd ~/.ssh (see that ssh directory exists or not)
     if exists then    
          $ ls
          $ config id_rsa.pub
          $ id_rsa known_hosts
          $ mkdir key_backup
          $ cp id_rsa* key_backup
          $ rm id_rsa*--
      if "not exists" then
          $ ssh-keygen -t rsa -C "your email"
8) heroku create
9) heroku keys:add
10) git push heroku master
11) heroku rake db:migrate.

To see the error in opening the site in the browser
  heroku logs --app app_name ( run that command on the terminal)

if git push heroku master gives following error

------Agent admitted failure to sign using the key.
Permission denied (publickey).
fatal: The remote end hung up unexpectedly

then run this on prompt

ssh-add ~/.ssh/id_rsa