How to register Microsoft Word 7

Does anyone know how to register Microsoft Word 2007 as your WordPress editor? I choose WordPress as my blog provider, click Next, and I’m presented with a “New WordPress Account” dialog that asks me to specify a “Blog Post URL.” It initializes this field to the following:

http://<Enter your blog URL here>/xmlrpc.php

I’ve got my WordPress installed at http://www.PhotoHelpDesk.net but entering that I get a simple “Word cannot register your account,” but doesn’t say why.

It also asks for “User Name” and “Password”. I type “admin” for my user name and the password associated with “admin” but I’m not sure if that’s what it’s asking for, either.