How do I do actions/scripts

I don't really understand how to create an action, but would like to do one which changes the tag title to Chapter 1, Chapter 2 etc. Looking at the guides I think it should be something like this - Chapter %_counter% but having entered that into the title field it doesn't work, however I cannot figure out how to create an action/script. I'm really sorry if I've butchered how the program works but I'm quite confused. Thanks.

Please have a look at the help files, including the steps to create an action:

https://help.mp3tag.de/options_format.html

Have a look at the FAQs:

[BanterLad365,
how do you want to find the number of "Chapter xx" ?
is 'xx' from the Track number?

then, you can do something like ' Chapter %track% ' in an Action,
so that the chapter number is grabbed from the number in the 'Track number' tag.

Thanks for the suggestion, I did go with this in the end when I figure out how actions worked.