The indoor stuff is all self-contained. You get a container with compressed sawdust already inoculated. You just wet the thing and mist it occasionally and all of a sudden you have amazing mushrooms with flavor that store bought cannot match.
For the outdoor stuff, I bought the plugs. You have to have some freshly cut logs or stomp. You drill holes into them and stuff the dowels with the spores already on them. They start to consume the log which takes 9 to 12 months. Once they run out of food, i.e. the log is fully colonized, they think they are going to die and they start to immediately "flower" (i.e. produce mushrooms) and you get a full harvest. Sometimes you have to shock them by sticking the logs in water for 24 hours. That makes them think there is a flood coming and fruit as soon as the soaking is over. Some people even slam the logs as to make the spores think the end of the world is really there
. We bought the plugs but had to throw them away as we got busy and didn't locate an appropriate log.
Note that you have to match the tree with the mushroom you want to grow. Their site lists the appropriate species that make good hosts. In general the tree has to have rough bark and be deciduous (there are some exceptions). The time to cut down the tree is now before the leaves come out but after the sugars start to run up the stomp.
There is also a way to grow them directly in soil but I am not attempting that as I worry about all the other species also growing.
This is a very nicely done video on this topic and while more than an hour long, is super educational and presented in such a friendly manner.