Take each sheet and glue them together one on top of each other. As soon as you apply glue, get C-clamps and use them all around the deck to tightly hold the deck as the glue cures. Use will need 4 to 8 C-clamps. The more the better. Place the deck with the clamps around it on 2 bricks kept wide apart and place something really heavy at the center. This will bend the deck. Once the glue is dry the deck will retain this shape.