Marilyn, each photograph in the database has a 'number' attached to it.
Using Londonderry as the example, go to the DB and find the Iris.
Click on the photograph you like best.
Just above that photograph will be a string of characters looking like this:
[db_photo]12003[/db_photo (I took the last square bracket off so you could see the string)
Copy that string in its entirety and paste into your thread/reply.