To create a new mailbox in order to be able to receive e-mail to your domain name, follow these steps.
Login to cPanel.
Under the 'Mail' section, click 'Email Accounts':
At the top of the page, you may enter the appropriate details for your new mailbox:
Once you've entered the necessary details, click 'Create Account' and your new mailbox will be created.
You may now configure the mailbox on your appropriate device(s). If you need assistance with this, please see the following KB article on how to automatically configure your mailbox.