Once the program is running, it will automatically recognize all the songs on your hard drive and it will look for the album covers online. No matter how weird it is, the program will find it.
Of course, you can also assign album covers manually by selecting any image on your hard drive, although the program is so effective that you won't need to. That said, sometimes it assigns images with poor quality.
Creevity is a very interesting application for users with lots of music on their hard drive, since it will let them tidy up their collection in the easiest way.