To add questions to your quiz you will need to return to the page where you generated the quiz in the first place. You don't need to waste time re-entering all of the questions that you already have in the quiz. Instead just enter your new questions and answers.

Once you have generated the script containing your new questions you can then add the code to the end of your existing quiz script instead of making a new one.

You then just delete those lines of code between the last of the previously existing questions and the first of the new ones since a copy of those lines already exists at the top of the script and a second copy is not required.

You can then reorder the questions to move the new questions to whereever you want them to be in the question order.