If purchased McAfee offline from a retail store: http://www.mcaf-ee.com/mcafeecomactivate/
Visit mcafeestore.com and register your McAfee Product.
Click My Account and sign in to your McAfee account, if exist.
If the account does not exist then create a new account using your registered email and password.
Now register your product by entering your McAfee product key.
McAfee product key can be found on the back side of the purchased McAfee retail card.
Scratch the McAfee retail card and enter the 25 digit McAfee product key in the required field then click submit.
Visit www.McAfee.com/Activate and sign in to your McAfee account.
Click install to start the download.
Enter your email id and address to sign in again if prompted.
Now follow the on-screen instructions to complete the McAfee installation process.
Click finish or close and you can now start using your McAfee product. http://www.mcaf-ee.com/mcafeecomactivate/