This is sort of hard to explain but i'll try
You know when you are sent to get the ingrediants out the store room in the dungeons for the polyjuice potion, and you go in to the dungeons and the first door on your left is the classroom and the first door on the right is just a room which has one of the green blob things on it so you get rid of it and theres a gargoyle which you cast your spell on and it makes the post in the corner sparkle so you can see a rope thing inside it, what is it for and what do yiu do with it?????, ive been trying to work it out for ages, it probably sounds stupid but im stuck

Help

You'll have to have a spell named Diffendo to tear the rope. You'll get that later in the game, I think, in a challenge. There's a secret hidden someplace there after you have torn the rope.

Thanks so much