Finish all the free gigs in a Career in Single or Band play.
Single: You must complete all free gigs on Expert by yourself.
Band: Every player (2-4) must have their difficulty set to Expert in order for the song to be completed as Expert.
*-If you complete the Career on Expert you will also unlock all difficulties below it. This is the same for all difficulties, not just Expert.
-If you are playing on a Guitar you can choose Bass as it is easier to play than Guitar.
-If you are playing Vocals you can hum the songs lyrics instead of singing, as this is much easier.