UCAS Qualifications

I've learned that I put in each class I've taken at a university, and how to do so, but for high school, after I've put in that I've received my high school diploma, do i need to put each class I took throughout the years under the modules? Or can I just leave it at that I received my diploma?

Has the university you're applying to asked for the classes you took at high school?

I haven't yet sent in the application to any of my choices. Will that be on the universities sites? Or do I submit the application first?

they should mention it somewhere, if not email them and ask

If none of them do/say they need those classes, I should be fine just leaving it saying I got my diploma, correct?