There are a few different ways to incubate yogurt. If you have a yogurt maker or Instant Pot with a yogurt setting, just follow the instructions that came with your unit. You can also incubate yogurt in your oven, with just the oven light turned on.
There are two basic types of cultures. Thermophilic and Mesophilic. The basic difference between them is the temperatures at which they need to be cultured. These two cultures can be made from either direct set or Heirloom starter cultures.