My grandmother made homemade yogurt all the time. As a little girl, I would get a kick out of watching the milk turn into yogurt.
4 cups milk
2 tablespoonfuls plain yogurt
Warm the milk to the point that if you stick your finger in it should be warm not hot (sorry this is the only way to test this. Put the warm milk into a clean bowl, now to ferment the yougurt put the 2 tablespoons of yogurt into the warm milk, mix well. Please make sure to mix this very well and cover with a lid. Then with a clean towell cover the entire bowl to keep it warm. The yogurt should be done anywhere between 8-10 hours. Then the yogurt can be placed in the refrigerator.
I love yogurt with honey, strawberries, or raspberries.