Quick Answer
Go back to your village once you have the milk.
How do you use milk in Warota?
Take the milk back to the village. Holding 100 milk in your inventory is not enough until you return home.
Get the milk
Make sure the milk is in your inventory.
Return to the village
Walk back to the village with the milk in your inventory.
Where do you find cows?
Cows and sheep are hidden at the far northwest end of the map. Take the Dairy Farmer hat and a rope, then bring the animals back to the village for milk and wool. Animals also respawn in dungeons.
How do you watch the Dairy Farmer tutorial again?
Open your inventory and use Luna's Guidebook. It replays every tutorial you have seen, along with other useful info.
FAQ
Yes. Use Luna's Guidebook from your inventory.
Yes. Return to the village once you have the milk.
See Warota Rancher for taming animals, or go back to Warota materials.