Actually, it's rather easy to make homemade yogurt. You need a 1 spoon of your favourite yogurt, 1 litre of fresh milk and a pot (or 2 jars). The spoons may be four, it's when you make yogurt you get the feel of the right quantity.

You boil the milk, you let it cool until it is hot, but drinkable. Then you stir well the yogurt into it.

You pour it into the jars (or the pot), wrap them carefully into a blanket or something similar. The idea is not to let it cool quickly. 

You leave it overnight and voila! The yogurt is ready. Not many things can go wrong, but be prepared for disappointments until you get it ;-)