Heat milk to 180 degrees F, stir frequently to prevent scorching. Hold at 180 degrees F for 10 min. Turn off heat. Add powdered milk, stir well. Place pan in a sink of cold water to reduce milk temp to 110 deg F, or just let it sit until the temp has dropped Remove from cold water Stir 1/2 to 1 cup of the warm milk into the plain yogurt until yogurt is smooth & dissolved Pour yogurt and milk mixture into the heated milk Add vanilla, stir very well There are many ways to incubate your yogurt. You don't need a yogurt maker but if you have one, follow your machines instructions. Allow the yogurt to incubate, undisturbed, for 9-10 hrs. Refrigerate. If you don't have a yogurt maker you can use a crock pot on low. You want to maintain the temp around 110 degrees during the incubation period. I've been successful by bring the crock pot yogurt temp up to 110 degrees then wrapping the crock in a heavy towel and sitting it in my oven (turned off) for 10 hours. Others use a cooler with a heating pad and yogurt inside and all wrapped in a blanket. I've never tried this but they say it works. Search the Internet for ideas, there are a lot of them out there Have fun and enjoy better yogurt and extra $$ in your pocket.