Your submitted link must be a "permalink" that will always go to your illustration for the particular topic, and not to your blog's or website's main page. This makes it easier for visitors to find your illustration related to that week's topic.

Your link may be deleted if it is not a permalink to a static page or single image.

To Link to a Static page: On a weblog, they're often called the 'Permalink' or 'Individual Entry Archive' pages. They're the pages that correspond to an individual post in your blog. Often, each post's title and/or date-time stamp is a permalink to just that single entry. Your permalink for posting the image in that post to Illustration Friday can be copied from there.
For example:

Incorrect:
http://www.example.com

CORRECT:
http://www.example.com/2006/04/entryname.html