Heat up the soldering iron, not too hot or else it might break some components.
Point one and two are in pictures 2 and 3 respectively.
An final overview is in picture 4.
5 and 6 show the switch.
7 shows what happens when your iron is too hot and you take too long to make a joint.
Make sure wiring runs stay clear of the black button pads, analogue stick movement and screw holes.