Don’t think you need any parts. There should be a vertical plastic locking bar that you should be able to see in the hole where you’ve removed the small rear section of the handle from. Ensure the locking bar is moved to the right (the rear edge of the door). Once you re-insert the part of the handle you have in your hand (photo 3) back into its hole on the door, the locking bar needs to be pushed to the left (the front of the car) through one of the two holes (your first photo) in the door edge to secure the handle back in place.
This video on YouTube might be of help - really poor quality, but the information you need is from about 2min 15 sec into the video - the lighting in the video improves at around 2min 23sec when you can clearly see the locking bar.
Edit; forgot to attach the link to the video!
. Here it is;
https://m.youtube.com/watch?v=hRCYRxrR2fk