Access the "Get Info" window in iTunes. Click "File" on the menu bar and choose "Get Info" from the drop-down menu.
Click the "Artwork" tab.
Copy your artwork. Click the image once, select "Edit" on the menu bar and choose "Copy" on the drop-down menu. If the image still appears in the "Artwork" window but fails to show up as an album cover, you may need to remove and reinsert it.
Click the "Delete" button directly beneath the image.
Paste the image back into the viewer. Click "Edit" on the menu bar and select "Paste" from the drop-down menu. Click "OK" when you finish.
Locate the missing artwork online. You can use any image browser, such as Google Images, Yahoo! Image Search or Bing Images (see Resources). Just type the name of the album into the "Search" box, such as "Beatles White Album."
Save the album cover image to your desktop. Click on any clear, high-quality version of the artwork to view the full size. Right-click the picture and select "Save Image As..." Choose your desktop as your destination so that you can easily locate the image for upload.
Access the "Get Info" window in iTunes. Click "File" on the menu bar and choose "Get Info" from the drop-down menu.
Click the "Artwork" tab.
Click the "Add" button and select your image from the desktop.
Click "OK."