Step 1: Create and author a badge as usual. Tutorial on creating and authoring badges here.

Step 2: At the bottom of the badge authoring page you'll see a toggle for Superbadge. Toggle this to activate superbadge.

Step 3: Click on "Add Sub-badges" and select all the badges that are required to be achieved before this superbadge is awarded.

The list of sub-badges will populate with the badges you've selected.

Note that expiry dates for a superbadge are dependent on its sub-badges.

A superbadge is expiring / expired if at least one of its sub-badges are expiring / expired.