I wondered the same question for a couple years. For some reason the language just wasn't sitting right with me, I couldn't really 'see' the process in my mind. Here's where I recently started.
fsre.nl They have free spores there if you are too bust to purchase. I got the texas strain. If money not a problem any of the above sites will do.
I then got on ebay and found some RYE bags. This is your substrate, where you will inject the spores and the mycelium will form.
Next I plan on injecting sterile water into the bag which contains my spore print, shake it, and suck it back up, and put that into a jar (through a tyvek filter or silicone of some kind) with a couple 100cc of sterile water.
You could also put just a couple drops on agar plates and watch what happens there too.
Use jar to make syringes. Inject 5-6cc into bags or jars of substrate.
The rest I'm still a little foggy on. But once fully colonized, the bags should be broken up, and dumped into a small tubberware or aluminum cooking tray, mixed with any assortment of nutrient goods, poo + straw + verm seem to be popular. Covered and allowed to colonize further, and then bam, fruiting. Which, I think happens with a little bit of light, a lot of moisture, and little water as possible on the shrooms themselves. Don't forget they need air exchange still.
I think that's about right. But DISCLAIMER, I'm inexperienced still.
Hit the shroomery and mycotopia grow FAQ or vaults. Tons of info. Here's a favorite thread of mine.
Daily Tek: Tips for Newbies @ mycotopia They also have a related syringe site I was unaware of for a while.
mycrotopia.com