Certbot from Let's Encrypt is the defacto method for installing and maintaining TLS certificates. Before you can use it on your new Ubuntu server you have to install it. Walk through the steps to install a TLS certificate with Nginx reverse-proxy
How to reboot or power down a system running Ubuntu
A very short list of essential Apache management commands for web hosting
Use the ServerName directive in Apache to resolve the "Could not reliably determine the server's fully qualified domain name" error message
Certbot from Let's Encrypt is the best thing going for installing and maintaining your site certificates. Use this simple one-line command to set it and forget it.
Certbot from Let's Encrypt is the defacto method for installing and maintaining TLS certificates. Before you can use it on your new Ubuntu server you have to install it. Use this easy one-liner to make it happen.
If your server's reverse-proxy is Apache, you'll need to set up VirtualHost blocks for each domain you're hosting. Here's a sample vhost.conf file you can use to get started.