Not able to create feature branch Git

Hi,

I am not able to push my feature branch using Git. I cloned using SSH and SSH 
key is also added.

arup@linux-wzza:~/Ruby/yzz> git status
# On branch posward
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       lib/yzz/posward_side.rb
nothing added to commit but untracked files present (use "git add" to track)
arup@linux-wzza:~/Ruby/yzz> git add lib/yzz/posward_side.rb
arup@linux-wzza:~/Ruby/yzz> git status
# On branch posward
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#       new file:   lib/yzz/posward_side.rb
#
arup@linux-wzza:~/Ruby/yzz> git commit -m "Yzz::Side is now refactord into 2 
classes, one of which is Yzz::PoswardSide."
[posward a31be0c] Yzz::Side is now refactord into 2 classes, one of which is 
Yzz::PoswardSide.
 1 file changed, 41 insertions(+)
 create mode 100644 lib/yzz/posward_side.rb
arup@linux-wzza:~/Ruby/yzz> git push origin posward
Warning: Permanently added the RSA host key for IP address '192.30.252.131' to 
the list of known hosts.
ERROR: Permission to boris-s/yzz.git denied to aruprakshit.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
arup@linux-wzza:~/Ruby/yzz> ls -al ~/.ssh
total 20
drwxr-xr-x  2 arup users 4096 May 27 00:17 .
drwxr-xr-x 44 arup users 4096 Aug 13 01:07 ..
-rw-------  1 arup users 1675 May 10 22:22 id_rsa
-rw-r--r--  1 arup users  408 May 10 22:22 id_rsa.pub
-rw-r--r--  1 arup users 2210 Aug 13 01:18 known_hosts
arup@linux-wzza:~/Ruby/yzz> xclip -sel clip < ~/.ssh/id_rsa.pub
arup@linux-wzza:~/Ruby/yzz> git push origin posward
ERROR: Permission to boris-s/yzz.git denied to aruprakshit.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
arup@linux-wzza:~/Ruby/yzz>



Can anyone tell me what is the problem ?

-- 
================
Regards,
Arup Rakshit
================
Debugging is twice as hard as writing the code in the first place. Therefore, 
if you write the code as cleverly as possible, you are, by definition, not 
smart enough to debug it.

--Brian Kernighan

On Wed, Aug 13, 2014 at 01:32:56AM +0630, Arup Rakshit wrote:

arup@linux-wzza:~/Ruby/yzz> git push origin posward
Warning: Permanently added the RSA host key for IP address '192.30.252.131' to 
the list of known hosts.
ERROR: Permission to boris-s/yzz.git denied to aruprakshit.
fatal: Could not read from remote repository.

It looks like you are pushing to GitHub here. You are fetching from user
boris-s, but you do not have write permission to push to his repository.

If boris-s is somebody you are working with and he would like to use a
shared repository workflow with you, ask him to follow this guide:

  https://help.github.com/articles/adding-collaborators-to-a-personal-repository

However, the normal workflow for most open-source projects is to make
your own fork with your changes, and then send a pull request to
boris-s. You can follow this guide:

  https://help.github.com/articles/fork-a-repo

-Peff