I followed the DO tutorial "How to secure Nginx with Let's Encrypt on Ubuntu 14.04," (https://www.digitalocean.com/community/tutorials/how-to-secure-nginx-with-let-s-encrypt-on-ubuntu-14-04) but when I open my site in...
Are you sure you followed whole tutorial you linked?
As far as I see, there is no any directive for SSL. Also it is listening on HTTP (80) port instead of HTTPS (443). [How To Secure Nginx with Let's Encrypt on Ubuntu...