@Sendy, user story #6 doesn’t say not to use iframe but if for some reason you don’t want to use it, your question is the perfect way to phrase it when you Google it.
Don’t directly link to someone else’s images from codepen or anywhere else, since the url may break, or they may even substitute a different image instead (and I’ve seen some nasty ones). Upload it somewhere like photobucket or cloudinary instead (don’t use imgur) and link to that instead.