This is just build using xampp, and I hope it helps you a lot.
You may found it in the index.php, where the INSERT query is there around line 127 to line 132 of the index.php
Basically, you may found this in the most of the file, but I created one file, where you can easily see the Read, and it is in the lists.php. I use read alsi for knowling if the user is exixted in the index.php, also auto complete in the update.php.
You may see this in the update.php. And I hope the code explains a lot.
Delete can be found in the lists.php. Around line 39 to 49. This is to lessen the file, also to make a one file coding inside of it.
Just go and download this repository, either using git clone, or download thru your desktop or mobile device with desktop mode.
I hope that this project will help you to learn the basics of CRUD with PHP and MySQL.