Dissolve the contents of the required number of capsules (one capsule per 1.5 to 2 liters of milk) in milk pre-heated to 45°C. Stir well until the starter culture is fully dissolved. Pour the cultured milk into prepared containers. Leave to coagulate at 45°C for 4 to 6 hours, then at room temperature for approximately 2 hours, and finally refrigerate for 8 hours.
See the detailed guide here.
The quality of the finished yoghurt depends on the quality of the fresh milk you use.
If the result is unsatisfactory, try different type of milk.