As simple as the description says.
All you have to do is to complete any mix, in any game mode (
besides the tutorial mode) and this trophy should unlock.
Note: If you are connected to the internet while playing the mix, after you complete the mix, your score will be automatically uploaded to the online leaderboard. This earns you
The Hello World trophy in DJ Hero worth 17 pointsHave your score posted to the online leaderboard.