Creating subdomain on Digital Ocean

Directory

html refers to main site.
demo , blog outside html (folder) refers to subdomain.

1. Create a directory from command line

 sudo touch /var/www/your-directory

2. Create a conf file on location /etc/apache2/site-available/

 sudo touch /etc/apache2/sites-available/your-directory-name.domainname.com.conf
 Just copy 000-default.config data to newly created file above by below command
 sudo cp /etc/apache2/sites-available/000-default.conf 
 /etc/apache2/site-available/your-directory-name.domainname.com.conf
 open file for edit 
 sudo nano /etc/apache2/sites-available/your-directory-name.domainname.com.conf
 and replace 
 DocumentRoot /var/www/your-directory-name
 sudo service apache2 reload.
 sudo service apache2 restart. 

3. After above proceee go to amazon hosted zone just follow below steps.

 Create a records set put name of your choice in name required fields
 Put www.yourdomain.com. in value and save records set. it will take 10-15 min to process by amazon.