Is the Dropbox application installed on your MAC computer? If
no then install Dropbox and then login to your Dropbox account. Dropbox would
automatically create a folder on your hard drive called Dropbox.
Is the application is already installed then Dropbox should
have a folder on your hard drive called Dropbox. Any files you save in Dropbox
should appear in the Dropbox folder. To import the photos into iPhoto, select
and drag the photos from the DropBox folder to the iPhoto icon in the Dock or
use the iPhoto file menu and then the Import command.