How to enable SSH login for new user in ubuntu (droplet digitalocean)?

Question

System administration

So. Pure ubuntu 14.04, vps on digitalocean.
I logged into the server as root via SSH.
I create a new user: I
adduser newuser
set a password for him, everything is as it should.
reboot. I try to log in via SSH to the server with the new user newuser, I get a refusal: Server refused our key
and I am prompted to simply enter the user's password, without an SSH password.
What should I do so that my user can log in to the server via SSH, entering only the passphrase of the SSH key?
Is there anything simple to get a couple of commands and that's it? Easier means better.

Answer 1

Add public key to ~/.ssh/authorized_keys file