Wordpress.com does not allow the iframe tag, nor do they allow plugins.
We then switch to the blogging platform and inserting the iframe statement to the theme, template, etc, for the blog or site. The actual HTML container for the iframe tag will depend on your blogging platform. This can be a plain div tag or a custom tag such as section for Posterous. The iframe invokes the page above.
Save your theme and verify that the Nomad or Headlines widget now appears on your blog.
(1) Be certain that the iframe dimensions are the same that you set in the Nomad or Headlines code.
(2) If you are not able to host a page yourself, you can check with a hosting provider that offer services for free. Another alternative could be setting up a public file in a service such a Dropbox.
Below are a few additional references. If you find a solution that works for you, feel free to drop us a line and we will share it with the community.
For others, such as WP.com and Posterous, Google pages.
If these instructions aren't helping with your issue, tweet us at @paper_li with your paper URL and name of browser and we can help further.