The springs labelled Part 5 are held in place by the pins Part 4. These should have a pin/clip to hold them in place on reassembly. Often a small R-clip.
Take a photo of the set up before replacing as a reference.
Replacing these is a simple enough job as you don’t need to take the pads out.
Changing pads means backing off the pistons in the calliper to leave room for the new and thicker pads to slip in. If no anti squeal inserts are used then Copper grease or other suitable non copper greases designed for brake use on the back of the new pad plates helps with squeal.
