Follow these steps to create a subdomain in cPanel:

1. Log in to your cPanel account.
For instructions on how to log in to your cPanel account, please click here.

2. Under the Domains section, click Domains.

3. Click the Create A New Domain button.

4. Enter the subdomain name you wish to add to the account and untick the 'Share document root' checkbox option. (If you have 'Share document root' enabled, the domain will show the same content as the main domain on the account. In this example, "create.example3.com" would be an alias for "demo.com". To achieve this, you can complete the process by pressing the Submit button here.)

Note: In recent updates, cPanel has migrated the functionality of Addon Domains and the creation of Subdomains under the Domains section, combining them.

5. After unticking the 'Share document root' option, it will present the option to configure your own directory for the domain. It will prefill the field by default, but you can edit it. When you are ready to proceed, click the Submit button.

6. Once completed, it will take you back to the Domains page, where you can see your newly added subdomain.