Fit all the 3D-puzzle pieces on the game board in such a way that it turns into a (flat) 2D-image. One of the protruding sides of each puzzle piece has 1 ball, the other side has 2 balls. So depending on how you orientate a puzzle piece, you get more or less balls. When solved, all puzzle pieces will fit on the game board without any holes uncovered.
Choose a challenge and put all the indicated pieces on the board.
Arrange all the 3D-puzzle pieces so all protruding parts fit into the holes of the game board.
You've found the right solution when all the puzzle pieces fit!