Making (and eating!) yogurt is one of the simplest and most satisfying pleasures in the kitchen.
1. Heat milk to 180 degrees (F)
2. Let the milk cool to 108-112 degrees (F)
3. Add starter*
4. Divide into jars and cover with lids
5. Leave your jars someplace warm...in a lightly warmed oven in the winter...on the counter in the summer
I like mine tart...so I'll leave it out for 24 hours. But generally if you leave it overnight, you'll have delicious yogurt in the morning.
*If you don't have access to someone with yogurt to borrow starter, you can get a starter powder in the store. The first generation won't have much flavor. But you can re-use a few spoons of your homemade yogurt as the starter moving forward. Each generation will successively develop great flavor.