As you play through Rock Band 3 you'll achieve goals of all kinds. You can check on your goals progress in game, but you can also track it on RockBand.com if you have linked your RockBand.com account with Rock Band 3.
To view your goals progress, sign in to your linked RockBand.com account and click on My Gameplay in the menu on the left. Then click on Goals. You'll be able to see a list of all Rock Band 3 goals and your progress. Goals you've completed with be bright and shiny, while goals you haven't yet completed will be faded.