nginx as a web proxy with ssl

I have installed proxmox and am running a simple ubuntu server where I have installed nginx. How and where do I setup ssl? I only want to use nginx to forward location to another web server. Can I set up Let's Encrypt ssl on the nginx server and forward to port 80 on the other web server or do I have to set up ssl on each of the targets?

I will have many dns names passing through the nginx proxy

yes, you can setup Let's Encrypt ssl on the nginx server and forward to port 80 of other web server.

You may find the answer/discussion on this similar post helpful, nginx as reverse proxy with several domains hosts

Let's Encrypt creates temporary files inside .well-known directory for authentication. This doesn't work when you're using nginx as a proxy. I think easiest thing you can do is to rewrite .well-known to a local, accessible location.

I'm adaption these instructions from Setup Let’s Encrypt with Nginx Reverse Proxy.

Open nginx config file for the domain,

nano /etc/nginx/sites-available/domain.com.conf

Paste following code before proxy settings,

location /.well-known {
        alias /var/www/something/html/.well-known;
}

Restart nginx

systemctl restart nginx.service

Try it!