cPanel offers a very simple point and click way to create subdomains in your hosting account.
You must first log into your cPanel hosting control panel - if you have lost or forgotten your username and/or password, you must email support and ask for the details (lost passwords will mean a password reset).
Once logged in, we will proceed with creating a sub domain in your cPanel web hosting control panel...
How to create a subdomain video tutorial...
First, click on the Subdomains icon 
in the Domains section
You'll come to the Subdomains page where there will be an entry section to add a subdomain and a list of existing subdomains lower down the page.
Note: If you have created any addon domains, subdomain entries will also been shown for each addon so bear in mind that not all of the subdomains listed may not be just subdomains.
Add a subdomain
Now we will add a subdomain (using the example shown in the video tutorial above). Go to the Create a Subdomain section and enter the name of the subdomain in the entry box titled 'Subdomain'. In this example we enter the name 'max'. This will create a subdomain as follows max.yourdomainname.com. You can choose which domain in your hosting to add the subdomain to from the drop down list of domains immediately to the right of that entry box.
When you click on the next entry box titled 'Document Root' cPanel will automatically create an entry based on the name of the subdomain. This will always be created in your public_html folder. So in this case cPanel will place public_html/max in that entry box. You can change this to what you want but you must always create the subdomain in your public_html folder, so it can be public_html/anything. This is the folder in which files for that subdomain will be stored, so you can the reasons why cPanel would choose something relevant to the name of the subdomain - its easier to see what relates to what when viewing your folders and files.
Now click the 'Create' button and the sub domain will be added by cPanel, you will see the details on the next page which confirms details of the subdomain and folder in use. Click the 'Go Back' link to return to the Subdomains page where the subdomain will now be listed.
You can now add files for that subdomain to the folder created for it.
