Hi: Here’s how you can add an additional WordPress.com blog to the original one you got upon registration:

  • choose “custom blog” as blog provider
  • select “WordPress” as your type of custom blog
  • change server api url to http://blogname.wordpress.com/xmlrpc.php
  • fill in your username and password The wizard will offer the additional blog for selection.

How to add more than 1 blog to a user account (Performancing.com)