Pretty self explanatory, start a solo tour and play all 21 songs on it, on any difficulty. Note that this runs on the RB1 engine, so it has to be done on guitar, drums, or vocals (can't do a solo bass career) and can't change instruments on a given tour. You only need to pass the songs, but try to average 4 stars per song so you can also get the "Ain't Settlin'" achievement at the same time.