Here, simply go down and down the stairs until you reach a door. Through it, you will find a big room. Here, go north. Your goal here is to make a stone pillar by placing one block above the other. Use Carry to move the stone into the square. Move it in the middle. Go up and Carry the other stone to make it fall down. Now go down and use Carry to place it on the middle one. You can then reach the stone tablet.