Hi HTD,
Here are instructions this part of the game, including how to operate the trap door:
Crystal Cavern
Do a big Gust over to the right to find a Melodia Idol on the ledge here. Drop down the cliff here. At the bottom you will see a switch. Stand on it and the door to the right will open. Unfortunately, as soon as you step off of the switch, the door closes. Use the Snowball Power to make a snowball. Drop the snowball onto the switch to weigh it down. Now head through the door.
There are a couple of Water Glorbs here. Use Cold Chill to freeze them until you can light the Beacon on the right. Once you have done this, you can burn them up with fire.
Light to torch to the left, then burn down the wooden gate nearby. Drop down the cliff here. At the bottom, create a snowball and smash the ice barrier to the right. Follow the ledges up here and you will see a lever on the left. This is behind an ice barrier that you can't break at the moment.
Proceed to the right and pull the lever up here. This will open the trap door to the left and allow snow to fall next to the ice barrier. Head over there and break the barrier with a snowball. You are now free to pull the lever.
This will open a door further to the left. Go through the door and deal with the Fire Glorb. Head to the left and use the drum to gain height. Up here, you can pull the lever and collect the Journal Page.
Head back down the way that you came. The lever will have opened a trap door above a switch. This will allow you to create a snowball and weigh the switch down with it. This will open the door to the right and you will be free to move onto Echo Cavern.
