How do i make a curtain with phisics in Roblox?

First off " thanks for the help, ill just go on the scripting requests website instead. whats the web adress?" I'm dead XD.

Okay, let's address the current situation.

a curtain that moves when the wind blows or if something falls on it / hits it.

It's possible but extremely hard. Fabric physics is a difficult thing to do since nothing in Roblox moves like fabric. So Roblox's engine doesn't have to account for fabric like stuff moving when touched. Another problem with this is Roblox doesn't have wind. You could make an algorithm for this easily but just wanted to throw that in there. So to answer your question it's possible but you would need to know intense amount of Lua and a crazy understanding on physics and advanced algorithms. There's no guide on how to do this because it fits a special niche that pretty much no one wants because using it in a large scale game would be ineffective.