how do you milk a cow?

Grab that utter and yank. There are many different correct ways to milk a cow, the best advice is to ask your local farmer, because they will know the best way for their cows.

Put the cow in a stanction or tie it to a post and clean off the udders(spigots) then put a bucket under the udders, Grab the udder at the part nearest the bag and wrap your thumb and forefinger around it firmly close the rest of your fingers and strip down the spigot pulling along its length. The milk will squirt out of the bottom of it into the pail. Repeat till no more comes out. Do this to all the udders.

It is important to remove as much milk as posssible to prevent mastitis or blockage of the udder. Giving the cow a little grain to eat will make the cow happier and it will let down its milk easier, if the cow is unhappy or doesn't like you it can make it A LOT harder to milk.