To add subdomain:

1. Click Sub Domain Management in DirectAdmin

2. Click Add Sub Domain

3. Type in your sub domain name and click "Add Sub Domain"

4. Your sub domain is automatically created under the directory "public_html/your_sub_domain_name"

5. Upload your files inside your sub domain directory or install your favorite CMS (wordpress/joomla etc) in the sud domain directory. 

Note: 

Each subdomain appears in public_html/subdomain-name.  This means that your subdomain can also be accessed at https://www.yoursite.com/subdomain-name.  You can upload to a subdomain folder in the same way you upload to any other folder: use FTP, MS FrontPage, File Manager, etc.