You can create an unlimited number of sub domains using your control panel.

Choose a name for your sub domain and enter it in the name filed as shown below:

Click the "add" button and your sub domain will be added automatically. 

Note: It may be several minutes before the sub domain activates on the server.

You have the option to redirect newly created sub domains to a different web site.

To upload files to your new sub domain, look for the new folder that has the same name as your sub domain in your public_html folder.

For example: http://php.mydomain.com is the same as http://mydomain.com/php ,

therefore, you should upload to your subdomain accordingly.

1)your public_html folder. 

2) Select your sub domain folder and upload your files using the built in file manager. You may also upload files using your FTP client or Microsoft FrontPage.

For further instructions on uploading files please consult the "file manager" section.