From AV Soft:
Art Fixer will read all your albums from the library and it will show the first album in the startup screen. You can browse your albums by using the Album box at the left top (or using the left and right buttons to the right of that box). When you clicked the "Fix" button, the fix window opens up. You can see several checkboxes (only the checkboxes that represent the problems for the current album are turned on by default). In this case the album art is generic. At the bottom of this window, you will notice that Google was searched for this album. You can navigate to the right image (preferably 200 by 200 pixels) and then you right-click that image. In the context menu you should choose "Save Picture As..." and save the picture to your desktop or my pictures folder. Art fixer monitors these folders for newly created .jpg images. If Art Fixer finds a new file, it will automatically use that picture.