You need to tell CFB what server CFB should use in order to preview the file.
So you need to associate a server with this Project. To do so, right click on Project -> Properties -> ColdFusion Server Settings.
Here from the dropdown of 'Servers' select the server that you added in CFB.
Once that is done, ensure that your project is in document root of the server which in your case could be the Inetpub\wwwroot.
Once this is done the preview should work.
Adobe ColdFusion Team
That appears to have me going, thank you.
This is not the most intuitive IDE environment I have used, and I have used several. Also there were many other problems besides this particular one. I was a bit too frustrated to write them down,
Whenever you can please do let us know what problems you are facing with the builder. If not in this release we would surely want to fix them in the next one.