I just made a batch a few months ago. If you go to your LHBS they should sell packets of Koji seeds and they should come with instructions. Also theres a ton of websites out there though they all say pretty much the same stuff. I'll give you a few of the good ones:
This recipe is the most comprehensive recipe i've seen so far. There are simplified ones but i say do it all the way. I know its a little hard to find Koji but check if there are some local japanese markets near your area. Koji is the great basis for miso soup, so if you're a fan of that, It'll be worth finding it.