Add artwork to content in Music on Mac
Songs, albums and music videos you buy from the iTunes Store or download from Apple Music come with artwork. You can also add your own artwork to any song or other item in your library.
You can add many types of still-image files, including JPEG, PNG, GIF, TIFF and Photoshop. You must convert WAV files to another format before you can add artwork to them.
You can also change the artwork for any playlist in your library.
Add artwork to music and video
In the Music app
on your Mac, click Songs in the sidebar.Select one or more songs in your music library, choose Song > Info, click Artwork, then do one of the following:
Click Add Artwork, select an image file, then click Open.
Drag the image file to the artwork area.
To retrieve album artwork from the iTunes Store for your entire library, choose File > Library > Get Album Artwork.
Change a playlist’s artwork
You can personalise any playlist by adding your own artwork.
In the Music app
on your Mac, select a playlist in the sidebar.Click the Edit button
(or click the More button 
, then choose Edit), then do one of the following:Click the Add button
, then choose an image file or an item from your photo library or drag an image file to the artwork area.Select one of the cover options (click the Back button
or Forward button 
to view all the choices).
Click Done.