How to create a hacking CTF challenge that uses XSS?

I need to create a reflective XSS CTF challenge for a project. I also want to make a stored XSS CTF challenge as well. I know how to perform these attacks since I’ve done them in multiple CTF’s, but I just don’t know how to create one. This CTF is meant for beginners and I am new to creating CTF’s. I’ve researched everywhere and asked multiple people but no one seems to know how to do this. Does anyone know how I can pull this off?