More details on how to embed zoom reg form into iframe (for non-tech webmasters)

Hi I was reading the locked posts asking about How to embed zoom reg form onto FTH site, I see @rtaylor posted an answer: 

"The Zoom pre-registration page can also be used in an iFrame. The limitation is that it won't launch the Zoom application when the pre-reg is submitted. One would have to go find the new Zoom email and click the 'join' link."

@Rtaylor can you please post some details (that would be understandable by a 5th grader) to help those of us who are not technical webmasters but help manage content on our club's websites so we can do this? I don't even know what an iFrame is or how to enter zoom pre-reg page into an iFrame on FTH site. I think many clubs (that are not corporate clubs) use Zoom and this info could potentially help many people. A youtube video plus a step-by-step written outline or transcript would be super helpful. 

Thank you
Edith Orenstein, SAA Club 7328 IEEE Live Wires Toastmasters Club (my corporate club uses webex and its not open to the public, but my other two clubs are community clubs and both use zoom: Club 3540 Morris Toastmasters, and Club 8761, Podmasters Advanced. )