This is part of my complete guide to Setting up a CentOS Digital Ocean droplet with Nginx for beginners.

I am assuming that your droplet/server is already created. The best practice here is to create an SSH key and have digital ocean install it during creation. This will ensure you can connect to your server as root immediately, without a root password existing. It is much safer than having a temporary root password. If you didn't do this, follow this guide to get connected to your server. Otherwise, connect as root with your ssh key.

Creating a new User

If you just need the commands, here they are. Read on for an explanation of what is happening.

adduser __username__  
passwd __username__  
gpasswd -a __username__ wheel  
su - __username__  
mkdir .ssh  
chmod 700 .ssh  
nano .ssh/authorized_keys #put your ssh key in here, 1 per line  
chmod 600 .ssh/authorized_keys  
nano /etc/ssh/sshd_config # uncommend and edit -> PermitRootLogin no  
systemctl reload sshd  

I am not going to bother repeating the excellent explanation of these commands from their source guide. If you are interested, check it out.