My b2evolution Version: 3.3.2

This may be really silly that I've missed it, but I'll ask anyway: I want to insert a container so that it (and, of course, its contents) shows up at the bottom of my post only when one clicks the "read more" or when the comments are shown in full. I don't want it to appear on the main page of the blog at all, only on the post's individual page. Where would I insert this container?

Thanks for any help!