An external backpack is where Open badges from various sources can be collected and displayed.
You would have to add these badges manually, to do this follow the steps below.
User Profile > Preferences > Manage badges
Select the badge you want to add to your backpack and click on the download icon
The badge will now download
You will need to access your external backpack (program/application) to be able to add the badge. (your backpack email address must be the same as your Totara platform one)
You will then need to follow the instructions on your backpack site to add the badges.