Hello Chuck,
After the Approver groups are built one relates the Approver group to an Endevor inventory area ( environment, system,type, etc). Then, when a package is cast it will review all the action's inventory area to see if an approver group has been related to that area. If one has been related that Approver Group will become associate to the package as part of the cast action. This is done automatically via the cast action.
For more information please see the Endevor Package Guide section on Determining Package Approvers.