What a beginner actually needs
Most advice aimed at running a webinar assumes you already have a stack: a place to host the page, a form tool, a way to issue links, a mailer for reminders, and the patience to wire them together. A first-timer does not want a stack. They want a session that fills and people who arrive.
So strip it to the four things that decide whether your webinar works, and leave the wiring to the tool: an invitation page that reads properly, sign-ups you can count against the seats you have, a private link for each attendee, and reminders before you go live. Nothing here needs you to touch settings you have never heard of.