"step 2"

this is where it gets really complicated, and, without wanting to scare you, it's also going to get even more complicated if you forget how you took it apart

on the plus side, the later cars are even more complicated

the central locking motors are screwed into the inner door skins in about the middle of the door, you should see 3 screws that hold them in place

undo these screws and then figure out how to unhook the motor from the metal bar it's hooked onto

once you've done this on both sides, you can progress to "step 3"