If you already have a registered barn address in your account, you are eligible for Barn Saver Shipping. Select the Free Barn Saver Shipping option when you're checking out, and your order will automatically ship free on your Barn Saver Shipping Day.
If you don't have a registered barn address in your account, you will need to add an existing commercial barn to your account, or create a new one in order to qualify for Free Barn Saver Shipping. Go to your Address Book, scroll down to "Add a new address" and click the box that reads "This is a commercial barn" (required). After this is saved, your barn address will automatically be assigned a Free Barn Saver Shipping Day.