First thing to do
Buat record dns jangan lupa (aku skip step ini karena bisa di googling ke web lain yak hehe, gampang kok)

Second
Buat vHost, cara-nya
vi /etc/nginx/conf.d/venom-www.conf

isi vHost-nya cenderung asal - asalan gapapa, contoh-nya kek di bawah ini

server {  
    listen 80;
    server_name www.fauzanooor.id;
    server_tokens off;
    location ~ {
        root /opt/mn/moon;
        index index.html index.htm;
    }
}

Kalo udah ya di save terus di restart nginx-nya
systemctl restart nginx

Third
Clone git certbot
git clone https://github.com/certbot/certbot

Kalo udah, masuk ke direktori-nya
cd certbot/

Fourth
Generate certificate, cara-nya gampang kok tinggal ketik ini
./certbot-auto

Terus pilih domain atau subdomain yang ingin memakai let's encrypt-nya

Which names would you like to activate HTTPS for?  
-------------------------------------------------------------------------------
1: fauzanooor.id  
2: www.fauzanooor.id  
-------------------------------------------------------------------------------
Select the appropriate numbers separated by commas and/or spaces, or leave input  
blank to select all options shown (Enter 'c' to cancel): 2  

tunggu sebentar, sampai ada pilihan domain-nya mau otomatis redirect dari HTTP ke HTTPS ga, kalo mau ketik angka 2 dan enter

Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.  
-------------------------------------------------------------------------------
1: No redirect - Make no further changes to the webserver configuration.  
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for  
new sites, or if you're confident your site works on HTTPS. You can undo this  
change by editing your web server's configuration.  
-------------------------------------------------------------------------------
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2  

Kalo berhasil, nanti muncul tulisan kek gini

IMPORTANT NOTES:  
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/www.fauzanooor.id/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/www.fauzanooor.id/privkey.pem
   Your cert will expire on 2018-01-04. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot-auto
   again with the "certonly" option. To non-interactively renew *all*
   of your certificates, run "certbot-auto renew"
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

udah gitu doang, selesai.