How cows make milk

A cow makes milk by eating grass, so they have to eat 70kg of grass to process milk,but how is it made?
First the  grass goes through the first two of the cows stomachs.
Next the cow burps which is made into cud. Cud is chewed for 1 minute. Cud travels through the
next two stomachs and is crushed up into small pieces.
Then the nutrients from the small pieces is absorbed into bloodstream.
This will help the cows make milk.
At last the cow gets milked and the milk goes away into the dairy trucks, to the factory.
Finally the milk is taken to the supermarket, where it is bought.