First heat the milk to pasteurize it
Then after it cools add the store bought yogurt and put it somewhere warm to "incubate"
I put mine in the crock pot on the "warm" setting. This keeps it at the perfect incubating temperature.
After about 12 hours I have a thick yogurt and put it in the fridge to cool.
Yogurt cheese is just yogurt put into cheesecloth in a strainer over a bowl until most of the whey (liquid yellow stuff) drains out. If left long enough its consistency is like cream cheese, if left for a shorter time its like sour cream and taste like it too. You can use it in place of sour cream in recipes with no taste difference. My sister said it is delicious (she's has very high standards on food) and compared it to her new favorite food Greek Yogurt.