http://www.ehow.com/how_4666202_make-yogurt.html How to Make Yogurt. Details for a more controlled method of making yogurt.
Here is how I make my simple plain yogurt.
http://www.durgan.org/URL/?WTQEP 10 November 2010 Yogurt.
Buy a small container of plain yogurt to use as starter bacteria. Gently bring to a boil a liter of milk. Pour into a glass bowl. Let cool to to just being slightly warm. Mix in about two large tablespoons of the starter yogurt.
Heat your oven to about 300 degrees, turn off and let cool a bit, then put the covered bowl in the oven and leave for 12 to 24 hours. At the end of the period presto, there is a large bowl of yogurt. Save a covered container of this yogurt for the next batch. Store in the refrigerator. I make a batch usually daily.