How to locate and update text files in CodeIgniter?

I've been tasked with managing a website built with CodeIgniter. The site mostly works fine, but there are two text files that need updating - one is a pop-up displayed when a user completes a form, and the other is an email confirmation sent to users. I've searched through the server files and database, but can't locate them. I have limited knowledge of CI and php, but this isn't a structural issue, I just need to find and update these files. Any suggestions on how to proceed: https://www.guru99.com/codeigniter-file-upload.html /koows ,  I know I'll need to learn more about CI/PHP, as this site will be my responsibility for the foreseeable future.