If I understand the rules correctly.
To set my playoff roster:
Promote Robert Covington to Active roster - $3.3m
Promote TJ Warren to Active roster - $3.4m
Demote Alex Len to Inactive roster - $0.8m
Demote Bryn Forbes to Inactive roster - $0.1m
Then since both Covington and Warren are injured,
Covington to Inactive, Len to Active
Warren to Inactive, Forbes to Active