These two user roles are set in slightly different places.
For information on the attributes of the various user roles see this article: Access Rights and Privacy Who Gets to See What.
These are set in the User list.
Select USERS from the main menu, and use the multi select menu on the right hand side of each employee to add/remove Admin status.
The 'Make Admin' option is only available for users with a registered email address.
To set the boss of a department head to SETTINGS > DEPARTMENTS.
Here you will see a column to set the Boss for each department.
Bosses can be any user so long as there is an email address against their profile.
If a user isn't appearing in the list then check they have an email address on their profile.