How to host my webpage using https or a domain

Hey, I am a beginner in the networking world, and I would like to host my HTML-JS webpage in DigitalOcean. I bought a web-hosting server with SSH access to install the packages needed to run my webpage.

So far, I have installed nginx and added my files to /var/www/html folder, then updated the /etc/nginx/sites-available/default to be something like the following:

server {
    listen 80 default_server;
    listen [::]:80 default_server;

    root /var/www/html;
    index index.html;

    server_name _;

    location / {
        try_files $uri $uri/ =404;
    }

Now it seems that I can access my webpage in http://ip of the DigitalOcean. I would like to do two things: one to access it via https://ip or using a domain name instead. Any ideas on how I can do these two things will be really helpful and welcomed. }