Log on to Easton's website and follow the "Warranty Policies" link.
Click on the "Bat Registration" tab and fill out the necessary information, making sure to enter the correct bat model and retailer where the bat was purchased. Also, hang on to your original receipt because you will need it if a warranty claim is submitted. (Resource 1)
Click on the "Submit" button at the bottom of the registration page and Easton will verify your information and register your bat.