How to allow ssh access using PubKeyAuthentication

hi sir

:~$ chmod 600 ~/.ssh/authorized_keys2
chmod: cannot access ‘/home/my user name/.ssh/authorized_keys2’: No such file or dire ctory
:~$ chmod 600 ~/.ssh/authorized_keys
chmod: cannot access ‘/home/my user name/.ssh/authorized_keys’: No such file or directory
:~$ ssh-keygen -t rsa -b 4096 -C “[email protected]
Generating public/private rsa key pair.
Enter file in which to save the key (/home/my user name/.ssh/id_rsa): ssh-add ~/.ssh/id_rsa
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Saving key “ssh-add ~/.ssh/id_rsa” failed: No such file or directory
:~$