New HP with 36 month AntiVirus Subscription

I purchased a new HP desktop from the HP online store which included a 36 month subscription to Norton Antivirus software.  At the moment, my 'trial' subscription is set to end in 5 days.  

 

The problem is I do not see any information on how to activate my 36 month subscription in the box my computer came in.

How do I activate the 36 month subscription that I already purchased?