Yep! You have to do toontasks to get "gag track training." There are 16 that you must complete before you actually will be able to use Toon-Up. You can check your progress in your shticker book--look at the page that looks like film. So when you get the choice of ToonTasks from an HQ officer, just look for one with "gag track training" as the reward.
Good luck!