Following command creates SSH key pair:
ssh-keygen
It will then prompt you for the location (the default ~/.ssh/id_rsa) and for a passphrase. The result will be two files, id_rsa (the private key) and id_rsa.pub (the public key). The public key will be store on this server while the private key will be copied into the client.
More details can be found here
Following command needs to be run on the server to push generated public key to SSH key repo:
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
This will append newly generated public key to existing authorized keys.
Finally appropriate permissions need to be set on the server:
chmod 600 ~/.ssh/authorized_keys
More details on SSH configuration can be found here