"Claiming a Listing" is done by your broker. They can claim it, alter it, update it and get credit for it here in Trulia. Trulia doesn't do FSBO's, so non-licensed people can't claim listings.
Contact your Broker and ask them to claim it. If they are not active here, they will have to set up a profile first.
Are you trying to sell it yoruself? likely what is happening is it is asking an agent if it was one of thier past sells. If you are trying to find out general info on your home county records where you bought the home will be your best start and comapir info on third party websites like Trulia to find any conflicting or any info not updated yet.