Onclick does nothing

Deborah, I recommend and going back and doing some tutorials on html, javascript, and php. Everything you've shown here indicates that if coded correctly, your function would work just fine.

The html you're using above won't work because it's not being written correctly. I'd recommend something like https://www.w3schools.com/html/ to get started.

The javascript you posted above is still incorrect and doesn't do anything. I'd recommend getting started with https://www.learn-js.org/ to get the basics of javascript.

For your php and back end, there are hundreds of resources, but I'd recommend some youtube videos that have some visuals to depict the difference between backend and frontend.

I'd slow down the roll on trying to blame the 'main developer' until you've written working code that is not working, but for the time being, it's just code that won't work in any environment.

Codeigniter is simply one of the tools you need to learn to be a successful developer. Always add more tools to your coding arsenal!