To earn this, you need to play at least one song from each decade up to the '00s. Every song you can export will cover all decades except for the '50s. The only artist with songs from this decade is Johnny Cash, browse through the DLC store and download any song which you like to contribute towards this goal.
For reference, here's a quick rundown on other decades.
- Gimme Shelter (The Rolling Stones)
?Rock Band 2
- Pinball Wizard (The Who)
- Spirit in the Sky (Norman Greenbaum)
?LEGO Rock Band
- Fire (The Jimi Hendrix Experience)
- I Want You Back (The Jackson 5)
Every other decade ('70s-'00s) is covered with the Blitz tracks, which will count towards this.