Installing letsencrypt:
 
sudo apt-get install letsencrypt
Configuring letsencrypt and getting certificates is almost trivial, in my case:
Sudo letsencrypt certonly --webroot  -w /var/www/html/ -d jvdm.info
Certificates land in:
/etc/letsencrypt/live/jvdm.info/privkey.pem
/etc/letsencrypt/live/jvdm.info/fullchain.pem
/etc/letsencrypt/live/jvdm.info/cert.pem
/etc/letsencrypt/live/jvdm.info/chain.pem
/etc/letsencrypt/live/jvdm.info
Configuring nginx to use https:
$ more /etc/nginx/sites-available/jvdm.info
# jvdm.info configuration
#
server {
    listen 80;
    return 301 https://$host$request_uri;
}

server {
  listen 443 ssl;
  server_name jvdm.info;
  ssl_certificate /etc/letsencrypt/live/jvdm.info/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/jvdm.info/privkey.pem;

  root /var/www/html;
  index index.php index.html;
  location / {
    try_files $uri $uri/ =404;
  }
  # for letsencrypt
  location ~ /.well-known {
    allow all;
  }
}