A backpack account allows badge recipients to store and share their badges - and even allows you to create collections of your badges.
To create a backpack account, visit https://app.openbadges.me/#!/signin and click "Register". You will then be prompted to register for an issuer or a backpack account. Choose the backpack account.
After validating your email address by clicking the link in the email sent to you, you will then be able to use your backpack account.