heroku deployment error , remote origin is already exit.

Hi everyone,
I had deployed my one project on HEROKU and url is
http://ankit.heroku.com. It’s working fine.
But when I am trying to deployed second project , getting some fatal
error. I am write my procedure here. I have some confusion please
clear it. I had googled but not find satisfactory answer.
Install gems are following
*** LOCAL GEMS ***
actionmailer (2.3.8, 2.0.2)
actionpack (2.3.8, 2.0.2)
activerecord (2.3.8, 2.0.2)
activeresource (2.3.8, 2.0.2)
activesupport (2.3.8, 2.0.2)
bundler (0.9.26)
capistrano (2.1.0)
cgi_multipart_eof_fix (2.5.0)
cmdparse (2.0.2)
configuration (1.2.0)
fxri (0.3.6)
fxruby (1.6.12 mswin32)
gem_plugin (0.2.3)
git (1.2.5)
heroku (2.0.4, 2.0.2, 1.20.1)
highline (1.4.0)
hpricot (0.6 mswin32)
launchy (0.3.7)
log4r (1.0.5)
mime-types (1.16)
mongrel (1.1.2 mswin32)
mysql (2.7.3 mswin32)
needle (1.3.0)
net-sftp (1.1.0)
net-ssh (1.1.2)
rack (1.1.0)
rails (2.3.8, 2.0.2)
rake (0.8.7, 0.8.1, 0.8.0, 0.7.3)
rest-client (1.6.1)
rmagick (2.12.0 mswin32)
rubygems-update (1.3.7, 1.0.1)
sources (0.0.1)
sqlite3-ruby (1.2.1 mswin32)
term-ansicolor (1.0.5)
will_paginate (2.3.14)
win32-api (1.0.4 mswin32)
win32-clipboard (0.4.3)
win32-dir (0.3.2)
win32-eventlog (0.4.6)
win32-file (0.5.4)
win32-file-stat (1.2.7)
win32-process (0.5.3)
win32-sapi (0.1.4)
win32-sound (0.4.1)
windows-api (0.2.0)
windows-pr (0.7.2)
My app name isbigstory
Git and heroku username is pravinmishra88
Email is  pravinmishra88
MY steps are following
C:\InstantRails-2.0-win_2\rails_apps>cd bigstory
C:\InstantRails-2.0-win_2\rails_apps\bigstory>git init
Reinitialized existing Git repository in
C:/InstantRails-2.0-win_2/rails_apps/bigstory/.git/

C:\InstantRails-2.0-win_2\rails_apps\bigstory>git add .

C:\InstantRails-2.0-win_2\rails_apps\bigstory>git commit -m "first commit"
# On branch master
nothing to commit (working directory clean)
Now opening my GIT BASH and there adding ssh key like that
$ ssh-keygen -t rsa -C “pravinmishra88@gmail.com”
Please clear one thing here,
WILL I AGAIN Add your SSH key to GitHub. One time I had added on time
of deployeding previous app.
Now on git bash command line moving to my app directory and
$ git remote add origin git@github.com:sanmugamk/sample.git
AND getting error here
Fatal: remote origin is already exit.
When typing
$ git push origin master
ERRor is
Ssh:github: no address associated width name
Fatal: the remote end hung up unexpectedly

I had google and find one solution he suggest
You already have a remote named origin, and it's still using the old,
invalid URL. Open up.git/config and change the URL for the origin
remote, or use the set-url subcommand for git remote:
And run
$ git remote set-url origin git@github.com:pravinmishra88/bigstory.git

I am not able to find where this file .git/config is located.

If this solution is true , help me where is directory is located.

If any wrong any my step help me

THANKS INADVANCE.

Hi everyone,
I had deployed my one project on HEROKU and url is
http://ankit.heroku.com. It’s working fine.
But when I am trying to deployed second project , getting some fatal
error. I am write my procedure here. I have some confusion please
clear it. I had googled but not find satisfactory answer.
Install gems are following
*** LOCAL GEMS ***
actionmailer (2.3.8, 2.0.2)
actionpack (2.3.8, 2.0.2)
activerecord (2.3.8, 2.0.2)
activeresource (2.3.8, 2.0.2)
activesupport (2.3.8, 2.0.2)
bundler (0.9.26)
capistrano (2.1.0)
cgi_multipart_eof_fix (2.5.0)
cmdparse (2.0.2)
configuration (1.2.0)
fxri (0.3.6)
fxruby (1.6.12 mswin32)
gem_plugin (0.2.3)
git (1.2.5)
heroku (2.0.4, 2.0.2, 1.20.1)
highline (1.4.0)
hpricot (0.6 mswin32)
launchy (0.3.7)
log4r (1.0.5)
mime-types (1.16)
mongrel (1.1.2 mswin32)
mysql (2.7.3 mswin32)
needle (1.3.0)
net-sftp (1.1.0)
net-ssh (1.1.2)
rack (1.1.0)
rails (2.3.8, 2.0.2)
rake (0.8.7, 0.8.1, 0.8.0, 0.7.3)
rest-client (1.6.1)
rmagick (2.12.0 mswin32)
rubygems-update (1.3.7, 1.0.1)
sources (0.0.1)
sqlite3-ruby (1.2.1 mswin32)
term-ansicolor (1.0.5)
will_paginate (2.3.14)
win32-api (1.0.4 mswin32)
win32-clipboard (0.4.3)
win32-dir (0.3.2)
win32-eventlog (0.4.6)
win32-file (0.5.4)
win32-file-stat (1.2.7)
win32-process (0.5.3)
win32-sapi (0.1.4)
win32-sound (0.4.1)
windows-api (0.2.0)
windows-pr (0.7.2)
My app name isbigstory
Git and heroku username is pravinmishra88
Email is  pravinmishra88
MY steps are following
C:\InstantRails-2.0-win_2\rails_apps>cd bigstory
C:\InstantRails-2.0-win_2\rails_apps\bigstory>git init
Reinitialized existing Git repository in
C:/InstantRails-2.0-win_2/rails_apps/bigstory/.git/

C:\InstantRails-2.0-win_2\rails_apps\bigstory>git add .

C:\InstantRails-2.0-win_2\rails_apps\bigstory>git commit -m "first commit"
# On branch master
nothing to commit (working directory clean)
Now opening my GIT BASH and there adding ssh key like that
$ ssh-keygen -t rsa -C “pravinmishra88@gmail.com”
Please clear one thing here,
WILL I AGAIN Add your SSH key to GitHub. One time I had added on time
of deployeding previous app.
Now on git bash command line moving to my app directory and
$ git remote add origin git@github.com:sanmugamk/sample.git
AND getting error here
Fatal: remote origin is already exit.
When typing
$ git push origin master
ERRor is
Ssh:github: no address associated width name
Fatal: the remote end hung up unexpectedly

I had google and find one solution he suggest
You already have a remote named origin, and it's still using the old,
invalid URL. Open up.git/config and change the URL for the origin
remote, or use the set-url subcommand for git remote:
And run
$ git remote set-url origin git@github.com:pravinmishra88/bigstory.git

I am not able to find where this file .git/config is located.

If this solution is true , help me where is directory is located.

If any wrong any my step help me

THANKS INADVANCE.