Bir kaç adres veriyorum, kontrol edersen mantığını anlayabilirsin.

http://talkerscode.com/webtricks/upload%20image%20to%20database%20and%20server%20using%20HTML,PHP%20and%20MySQL.php

http://codewithawa.com/posts/image-upload-using-php-and-mysql-database

https://www.codexworld.com/upload-store-image-file-in-database-using-php-mysql/