Uh, the balance bars! You have to mantain them in the “grey zone” (green and red recall the color of the cards that push in that direction).
There are 4 bars (one for each zone: north, south, east, west) and you have to keep them “balanced”: the value -indicated in the box next to it- must remain between “-20” and “20”. With -21 (due to the green cards) or 21 (due to the red cards), you lose.
And… under “Settings”, you can re-open the tutorial at any time :)