In order to post a rental listing on Trulia, your account must indicate that you area a landlord. It looks as though you changed that once you posted your listing. In order to edit your listing, you'll need to change your account back to 'landlord'. You will then have access to a My Listings section of your account. In that section, click on the 'Rent' tab and your listing should be available for you to update as needed.
Let us know if you have any other questions.