Both of these tabs are passive areas, in that there is no functionality other than the opportunity for you to review elements.
Contracts are attached to Catalogue items (Releases, Tracks, Works) via their respective areas in the Catalogue section. Any items that have been linked to a contract will be displayed here.
Costs are uploaded or entered in the Sales area. Again, this is simply a reference area to view at a glance what costs have been associated with this contract. As Costs are rarely every recouped from songwriters, the Cost feature is not available for Publisher clients.