To find all the Puzzle Pieces in Level 6-6, Crumble Canyon, in Donkey Kong Country Returns, follow these detailed steps:

1. Start of the Level:
– At the beginning of the level, turn back and blow on the blue plant hidden behind a wooden wall. This will reveal the first Puzzle Piece.

2. After First Barrel Cannon:
– After getting launched by the first Barrel Cannon, go back and destroy the cactus to find the second Puzzle Piece.

3. Behind Wooden Boards:
– Soon after the first DK Barrel, find the Puzzle Piece behind some boards above a teetering platform with a Skellirex on it.

4. Bonus Level:
– When launched to the foreground by the Barrel Cannon after the first checkpoint, go to the left up a rocky hill to reach a hidden Barrel Cannon that shoots you into a hole in a rock. Inside this hole is a Bonus Level where you must collect 44 bananas and four Banana Coins above a moving trampoline within thirty seconds to earn a Puzzle Piece.

5. Giant Dinosaur Skull:
– While running away from the big, round boulder, see a giant dinosaur skull and jump into its mouth to collect the hidden Puzzle Piece.

6. Blue Plant Near Fifth Puzzle Piece:
– Near the fifth Puzzle Piece, there is a little blue plant. Blow on it to reveal another Puzzle Piece.

7. Tunnel Area:
– Shortly after the letter N in the tunnel area, see some boards and jump off from the wooden boards below them to reach the Puzzle Piece.

8. Between Wooden Walls:
– Immediately before the letter G, find the eighth Puzzle Piece between two wooden walls.

9. Final Area:
– In the final area, where the Slot Machine Barrel is located, fall down into the tar to find the ninth and final Puzzle Piece under the platform supporting the Slot Machine Barrel.

By following these steps, you should be able to collect all nine Puzzle Pieces in Level 6-6, Crumble Canyon.