I didn't want to give up, though, so I looked it up on the internet. I went to this site and this site and cobbled together a technique that worked for me! It uses a crock pot as a source of heat.
1/2 gallon of milk (whatever kind you want)
2 TBSP yogurt
Heat milk in crock pot on low for two and a half hours. This kills all bacteria and cultures so the ones you put in it will be the only ones. Unplug and allow to cool in pot for three hours. Take a cup of the heated milk out and whisk in the yogurt. Stir the starter-yogurt mix into the rest of the milk. Replace cover, wrap pot in wool blanket or towels and place in an UNHEATED AND OFF oven with the oven light on. This will keep the milk at the right temperature to turn it into yogurt. Let sit ten to twelve hours or overnight. Do not open the door! You'll disturb the yogurt-fairy and ruin a half gallon of milk.
Store yogurt in the fridge in a covered container. I used a quart canning jar.
I have put honey, fruit, and my homemade granola in it. Put the granola on right before you eat it, though, or it will get soggy.