There are a lot of different mechanics in Spiritfarer that you will need to learn as you help the Spirits move on to the afterlife, but not all of them are well explained.
One of those mechanics is the Windmill, which is one of the buildings you can build on your boat and will help you grind the grains into flour. Just purchase Albert's Craftsman upgrade so you can build it.
Now, how to use the thing ...
Use of the windmill
First go up to the middle level of the windmill and interact with the compartment there. You can do this by pressing Square on PlayStation 4, X on Xbox One, and Y on Nintendo Switch. Place the beans in the compartment, then go to the next step.
Climb to the top of the windmill and interact with the column there. This will allow you to change the level of the windmill, which is seen as a square that you can move up or down with the D-Pad. You will see a smaller wheel on the right, which is what you want to spin.
Adjust the level of the windmill until the wheel begins to spin. As long as that wheel spins, that's how you know the mill is grinding the grain. Just pay attention to this wheel and spin it.
Once you have crushed all the grain, you will automatically be removed from the column and know you are done!
It's pretty straightforward once you know what you're doing with it and start the process. It's very similar to chopping wood or melting metals, with just a bit more interaction between players.
With this knowledge, you can cook all kinds of delicious food for the finicky spirits you meet.
