server {
    listen :80;
    listen [::]:80;
    server_name example.org;
    root /foo/bar;

    ssl on;
    ssl_certificate /path/to/public/certificate;
    ssl_certificate_key /path/to/private/key;

    ...
}

echo | openssl s_client -connect your.domain.com:443 | openssl x509 -noout -dates

sudo service nginx reload