Click on the song once using your mouse so that it highlights in iTunes. Right click using your mouse and select "Get Info." You can also click once in the artist column next to the song you want to edit. A small box will populate where you can type in the artist details.
Navigate to the "Info" tab. Type in the artist information in the box marked "Artist." Click "OK" and the changes will immediately populate in iTunes.
Install a third-party software of your choosing if you have multiple artists that need to be edited. Drag-and-drop the songs you would like to be fixed into the software editing box, which is attached to iTunes. The system will search its database of millions of artists and songs and input the artist information as well as artwork and other details about the album for you.