As a prerequisite you need a twitter account for reasons of authentification. And furthermore you need to have enabled the plugin IndiePub in Known.
This e-mail I wrote:
2) Enter your domain. Mine is e.g. petersell.com
3) Click Authorize.
4) Choose an authentification provider
5) Click Continue
6) Click on Email and note your new email address given by Quill.
7) Write your email and send it to your Quill email address. Enjoy your new post at your withknown site. This was my resulting post.