Step 1 - Choose a Blogging Service Type
Push the F8 key on your keyboard to activate PFF. On the right side of the screen you will see a button labeled Launch Account Wizard. Click it and you will see a window like this appear:

Select Custom Blog and click Continue.

Step 2 - Enter the API information
Blogging clients such as PFF can communicate with our servers through what's known as an API, an Application Programming Interface. In this step, we need to tell PFF what API we support, and the address through which it can access that API.

Choose MetaWeblog API from the first dropdown menu, enter https://www.blogware.com/xmlrpc.cgi in the Server API URL field, then click Continue.

Step 3 - Enter your Login Information
Now you'll enter your BlogHarbor username and password, and click Continue.

Step 4 - Confirm your Blog Address
If everything's been entered in correctly to this point, you'll see a list of BlogHarbor blogs you manage using the account you specified in the previous step. Nothing to do here but click Continue.

Step 5 - Account Added
Not sure if being finished counts as a step, but in this step PFF will let you know that configuration is complete and you can now start using the PFF extension to post to your blog.

Now would be a great time to read the Performancing for Firefox Handbook to learn all about how to use the extension to post to your blog.