Hi, I was a collaborator on this game, so I'll try to help. The controls should be below the game page if you scroll down. The aim is to use the ingredients to create a requested potion. The potion you need to make is shown when you look at the bucket on the rope. You mix ingredients by ringing the bell with the ingredient you want, then placing them in the cauldron. You'll notice that some of the ingredients require time to pass in order to get them - there should be a bed in the corner of the room where you can sleep and go to the next day, then the ingredients will have progressed to the next stage. The goal is to create one of every potion listed on the board at the back of the room in as few days as possible.
Sorry for the ramble. Hopefully this helps :)