You can choose from a number of applications that take existing MP3 files and add album art to the MP3 metadata, which portable MP3 players and other players can then use. The free, basic version suits my needs just fine, but you can also choose the gold version, which requires registration.
The process is simplified or complicated by the quality of information already available in the music file.
In Windows Media Player, go to the album tab and select the album that you need to add ID3 tags to.
Once the tracks are visible, select all the tracks and select "Auto-Tag from Amazon," which will connect you to Amazon for information about the selected songs.
If you don't see a match in the Amazon search area, you can type other search words, and at the bottom of the screen you'll see the matches the program makes.
Right-click the album art image and select ‘Copy’ from the context menu.