To create the subdomain please follow the below mentioned steps:
1: Open the cpanel with the login link and the details which you have received on your registered mail id.
2: Under the DOMAIN section you will find the option named as " SUBDOMAINS", click on it.
3: Under the Create Sub Domain section you need to fill the details as subdomian name and the domain name from which you are creating the subdomain and you do need to fill the directory manually it will appear automatically.
4: Once you done click on Create.
NOTE: ** Once you create the SUBDOMIAN it will take maximum 24-48 hours for it to propagate**
