[Owncloud] How to contribute to Admin Documentation?

[Arman Khalatyan]

Hi, I wrote some steps to setup HA-Linux with CentOS(or Ubuntu) with
Owncloud on two nodes.
I wish to push the changes to git .
I followed the steps on
https://github.com/owncloud/documentation/blob/master/CONTRIBUTING.rst
The final step to push to github is unclear.
If I do:
git commit -m "HA-Linuix with OC instance"
git push
the push failed with
fatal: remote error:
  You can't push to git://github.com/owncloud/documentation.git

What is the next step after commit to local. Should I request merge ?
Sorry, but I am new in git.
Can someone advice me how to proceed further?
Thanks,
Arman