SSH access using .pub key
You got it the wrong way round :-)


create a key pair on the Mac you are using 
put both id_rsa.pub and id_rsa into ~/.ssh and run chmod 600 id_rsa
append the generated public key (id_rsa.pub) to .ssh/authorized_keys on the remote machine (your server in this case). If you are allowed to login in via ssh using a password, use

ssh remoteuser@remotemachine "mkdir ~/.ssh; cat &gt;&gt; ~/.ssh/authorized_keys" &lt; ~/.ssh/id_rsa.pub


otherwise transfer the file by whatever means you have to upload files.
run ssh remoteuser@remotemachine in your shell to connect


PS: The private key should never need to leave the machine it's generated on