1. Use the "Force Push" ability: Use a Jedi or a character with the Force Push ability (like Chewbacca) to push the large trash compactor into the door.
2. Destroy the door: Once the trash compactor is inside, destroy the door by attacking it with your lightsaber or blaster.
This will open up a new path to Jabba's palace and allow you to continue the game.
Let me know if you have any other questions about Lego Star Wars II!