A subdomain is a subsection of your website that can exist as a new website without a new domain name. Use subdomains to create memorable URLs for different content areas of your site. For example, you can create a subdomain for your blog that is accessible through blog.example.com and www.example.com/blog
Watch this video, to learn how to add sub domains in CPanel Web Hosting
Note: We assume that you are using the dns or nameserver that we sent to you during registration and it should work without any issues. If your DNS is managed else where or if you are using a third party DNS, then you must add necessary records at your DNS manager or domain registrar to ensure proper working.