All you do is wrap up the yoghurt in some muslin & tie it to a spoon to hang over a bowl for 24 hours. What happens is the curds& whey separate; the curds are the cheese& the whey is the liquid – which drips into the bowl. If you’re using kefir grains, it’s a good idea to put them in a nut milk bag or similar so you can find them again after the yoghurt’s thickened.
When it’s done, it’ll be nice as it is, but a bit of salt & pepper, & onion& garlic powders transform it into absolute deliciousness to spread on just about anything.