Write a post on your own site, and mark it up with the Microformats markup for an h-entry.
To submit someone else's post, create a bookmark post on your site linking to it.
If your website sends Webmentions automatically, then your post will be submitted as soon as you post it to your website! Otherwise, you can enter your post's URL below.
IndieNews will fetch the page from your site and look for the h-entry markup to find the post title and author.