Add object in list viewer when clicking on a button

Hi, I have a question about list viewers.

In my app, I want to be able to add a text item in my list viewer when clicking on a button. I want the item to be named after a variable saved earlier in my app, which is a chapter title. If the person hasn’t named their chapter title yet, I want to item to be named Chapter + the number of the chapter. (ex. chapter 1 which is the first chapter etc.)

If anyone can explain the blocks to me, thank you!