Select a new itinerary on the same airline as your ticket credit. Complete your reservation as usual. When the ticketing agent at CBT fulfills your ticket order they will apply your credit and charge any applicable change fee to your credit card on file. If there is a residual value left over, that will appear in your unused ticket list in AirPortal. If your credit is all used it will disappear from your unused ticket list. Some airlines allow a residual credit and some do not. Some allow the change fee to be taken out of the credit and some require you to pay it separately.
Agent-made reservations do sync to Concur. They will appear under 'My Trips' and 'Upcoming Trips' on the landing page in Concur.
On the Home travel page, review the Upcoming Trips section. For more detailed information, click the appropriate trip name in the Trip Name/Description column.