To post a comment on any is-blogging account, you must have an is-blogging username.

To create a is-blogging username goto the signup page, and just check username only.  (if you want to create your own blog, you are more than welcome to do that too!)

Once you’ve signed up at is-blogging, your username should be able to comment at any is-blogging site.

NOTE:  I discovered a bug when you use usernames with uppercase letters you’ll never be allowed to login.  So please use lowercase letters to create your usernames.   You can always change the appearance of your username using the ‘Display name publicly as:’ selection on your User Profile page.