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).
You must have at least one email set in the contact information section in cpanel, this is to receive notices about your hosting account and other notifications (including space/bandwidth alerts). You should never use an email address of any domain you have in your hosting account, it must be a separate email, preferably the address set up with your ISP.
Once logged in, we will proceed with changing or adding your contact email in your cPanel web hosting control panel...
Change or Add contact info video tutorial...
First, click on the Change Style icon 
in the Preferences section
You'll see a page called 'Contact Information & Preferences' which all existing settings (email and notification preferences).
You must add at least one email address - the first address going into the first text box. It is always a good idea to select all three check boxes against the various limit alerts, please do so to ensure that you are notified when your quota settings are coming close to being reached. This will give you the opportunity to reduce quota usage by deleting files/emails or to set higher quota limits. Once done, click the 'Save' button to retain the settings and make them active.
