There are colors. Red, green and blue. The puzzle is about mixing 2 of them at each step of the puzzle. If you still have troubles, look up a mixing scheme online.
Each step of the puzzles has 3 balls. The mixed color is in the middle. Original colors that big crystals have at the start are on the sides. Pick up the grey orb, color it with the active crystals. Pick up the newly colored orb and place it on the empty socket before closed gates.
What's the problem?