iPod 7th Generation not showing album covers

I just purchased an iPod Nano 7th Generation and when importing all of my songs, none of them show their respective album cover. This is even though I have uploaded each album cover to the song through iTunes' "artwork" tab and on, which I saw is the supposed method online. I'm a novice when it comes to technology, and I honestly do not really understand how this is all supposed to work. If anyone has a fix, please let me know! I have over 800 songs so if it is really tedious, I might just give up and not do it but hopefully that is not the case!

[Edited by Moderator]