Academia, in any form of teaching, is best described as being thrown into the deep end without anything to help you float, and learning how to tread water.
I've found on numerous occasions that I've just had to figure it out as I go along, there are no prep materials etc. You have to at some point, take initiative to figure it out and do the best you can.
Most tutorials that I have run I was never given preparatory materials. I had to develop these myself based on the topic.
The beauty of academia, and the curse, is the incredibly high level of autonomy that you might run into, and this can be rather confronting when you're looking for guidance and structure.
Just do the best you can, fake it till you make it, and so on. Not the best advice by any means, but hopefully it'll help you get by!