How to establish ssh connection?

Question

git

Generated keys . I ssh-keygen -t rsa
added ssh-add <путь к файлу ключей>it from the server root so that there would be no error, i.

ssh-add /var/www/dom/data/www/mydomain.ru/ssh/id_rsa

or it was necessary to specify to id_rsa.pub a key?
Test:ssh github.com

The authenticity of host 'github.com (192.30.253.113)' can't be established.
RSA key fingerprint is 17:27:ac:b5:78:28:3d:36:23:1b:56:4d:eb:df:a6:48.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'github.com,192.30.253.113' (RSA) to the list of known hosts.

I press yes the known hosts file, I don’t know whether it was created somewhere or not, I looked through the folders - nowhere. Ok let's continue:
ssh github.com

Permission denied (public key).

Then I created known_hosts manually and entered the address + key into it, but the result is the same.
What is wrong, and most importantly, how to diagnose this step by step? (does, for example, git know about the presence of the known_hosts file, does it see the correct path to the keys generated in the first step)

Answer 1

it is logical - why should there be access to the github server? Yes, even without user instructions.
https://help.github.com/articles/connecting-to-git...