You will need:
First, in a medium to large sauce pan, heat the milk to 185 degrees which will be just when the milk begins to come to a full bubble. I like to use my candy thermometer ($10 at most stores like Target or Walmart) for this step.
While waiting for the milk to heat do three things:
Make sure the water cannot get into the milk. Let the milk set until it cools to somewhere between 90-110 degrees. This takes about 10 minutes. Again, you can use the candy thermometer for this, or you can dip a clean finger into the milk. If you burn your finger, it's still too hot. If you don't have to jerk your finger out of the milk, presto...it's ready.
Remove a small amount of cooled milk, about a cup or so, and pour it into the bowl with the yogurt starter and mix well.
Pour BOTH the small bowl and the rest of the cooled milk into your preheated crock pot and stir gently.
Cover the crock pot completely with a thick towel or two. Place the lid onto the crock pot and immediately unplug it.
Walk away for 8-10 hours. If you make this in the evening while you are cleaning up the dinner dishes, this means that you literally go to bed and sleep while the yogurt makes itself, or as we seasoned yogurt makers say, while the yogurt cultures.
When 10 hours or so has elapsed (longer is fine), wake up and tell your fresh yogurt--your HOMEMADE yogurt-- Good Morning!
After the culturing process is complete, set your crock pot (or inner part of the crock pot if yours is the kind with a removable bowl) into the fridge for the yogurt to cool. Don't jostle it around much if you can help it. Just let it set peacefully. This allows the yogurt to become nicely firm and creamy. Let it cool for at least 4-5 hours or so (the longer the better).
Now, you've got yogurt--HOMEMADE yogurt. You'll want to dip it out into sealed containers for storing conveniently in your refrigerator. Don't forget to set aside some starter yogurt for the next batch if you're so inclined.
The yogurt-- the HOMEMADE yogurt-- is not sweetened like the flavored yogurts you may be used to. One of the perks of making your own is that you can sweeten it exactly as you wish with sugar, honey, artificial sweetener, or the peach jam you made from the South Carolina peaches you received earlier in the summer. You can choose whatever fruit you have on hand, or no fruit at all! Other toppings include granola, your favorite dried cereal, wheat germ, the list is endless!
You can make as large of a recipe as you wish. Simply use 1 Tablespoon of active yogurt per 2 cups of milk. Generally the yield of yogurt is equal to the amount of milk you used.