Here is a link to the pin outs for the tube sockets used in the 2Stroke (and most others)
The 12AX7 is a “dual triode” tube, meaning that it’s actually two preamp triode tubes in one envelope. There are two anodes (pins 1 & 6), two cathodes (pins 3 & eight), two grid (pins 2 & 7), Pin 9 is the center tap for the heater (6.3v) circuit and pins 4 & 5 are for the other side of the heater circuit (which are bridges together in this application). Tube sockets can have the numbers in different places (or none at all) but the pins outs will always be the same for a 12AX7. There is a blank space on the tube between pin 1 and pin 9.
Reading through the first sections of DH’s book will give you an overview of what the components do and how they relate to each other.
Depending on the component, it could be chosen for filtering, voltage control or reduction, tone shaping and so on. Read through the past forum posts here on the TAN site. Many of the posts are regarding the 2Stroke build and you’ll will find some common construction issues.
Everyone hear had a first build once upon a time, so ask all the questions you want, we’ve all been there.