The tutorial of o2jam typically opens when you begin to play for the first time. Otherwise, it can be accessed by clicking the "tutorial" button at the top right of the screen.
If beginners carefully listen to the instructions properly, it's easy enough that they can full combo the tutorial.
(Beginners are called beginners because they haven't fully coordinated the keys with their hands. I don't think it's possible for a first-time beginner to full combo anything)