Scald some full cream milk, which means heat it up until you get tiny bubbles on the surface and a skin starting to form. I do 2L batches, but any size should work.
Stick it in a container and stir in a spoon of live culture yoghurt, this is the starter, keep between 37 and 45 degrees C for 8 hours to ferment, strain with cheesecloth, or an old sheet in a colander, for 1.5 hours, cool in the fridge and serve.
I have a funky old swing top coffee jar, and another metal jar that I use for the fermenting. To keep it hot, I stick the jars in an old styrofoam 6 pack esky and add hot water from the tap every few hours, draining and filling the esky when it gets too full.
After straining, I get about 1L of yoghurt and 1L of whey. I tried to make ricotta out of the whey, by boiling for 15 minutes, I got some lovely tasty ricotta out of it, only a half a spoon tho!
The yoghurt that comes out at the end is the tastiest creamiest yoghurt I've ever tasted! Better even than the Jalna stuff. It's full cream yoghurt, so lots of the yummy fats. I add a spoon of honey to take the bite off the tanginess, you can add whatever you prefer to it, but it's quite good by itself too.
And for your next batch, put a spoon or two of the yoghurt into a smaller container, you then use that as your live culture starter, instead of the store bought stuff :)