Well, I guess I do it a more complicated way than I should.
First, if I don't know the album of a song, I google the song and find the album.
I then google image the album name and look for the best looking/correct album.
I copy and paste that into a MSpaint "project"
Save that
Go into itunes and in the about song, I pick the album cover from whatever I saved the picture as.
and then give the Album a name, and the artist if it was not already provided.