Yogurt is easy to make. Get some milk, heat it to 170° or so ± 10°, cool it as quickly as you can, covered, andn when it gets to 105° or so add the culture (that can be from another container of yogurt, or you can get dried yogurt culture tablets at places like Sherwyn's on Diversey). Try to avoid yogurts that have gelatin in the ingredient list ... ideally, you'll want to use a yogurt that says "live cultures" on the label ... but not all the ones with live cultures include that. The Greek yogurts should work well.
Keep the innoculated milk at warm room temperature (the temperatures outside today are near-perfect) for 12 - 24 hours. Then you have yogurt. Longer will make it firmer and a little more tart - that's up to your taste.
If the whey separates a little bit, you can put the yogurt into a coffee filter and let it drain some more ... then you have yogurt cheese ... a great ingredient that can substitute for ricotta, marscapone, etc.