I do, it's very easy.
You just heat up one liter of milk until is warm, not hot. A good measure is to put your clean finger in it and be able to have in there for ten seconds without getting uncomfortable or burnt.
Then you mix in a bowl the warm milk and one unflavored yogurt. Here you find Yogs (Sancor) and Dahi. You can also use the natural Activia which is unflavored but sweetened, it depends on wheter you're gona eat it sweet or not.
You cover the bowl with some dishtowels or a heavy towel and you let it sit overnight.
The next morning you'll have yogurt.