Any question answered...

The internet was invented so that you don't have to. The resource exists on a web server, make it accessible to whoever you want to show it to and post a link on the forum.

Er, yes. But I want the frame embedded in a forum post, not as an external link.

You can get the HTML to publish it, but obviously PHPBB forums don't allow HTML code in the posts and running [code] or any other tags around it doesn't work.