Problem with the URLS file

[tatiblockchain]

In the urls file, this line here:
url(r'^filebrowser/', include(fb_site.urls)),

gives an error, I looked at your example code: at the top you import site
from filebrowser.sites import site as fb_site

This line gives an error, so such module fb_site. I looked at the packages, filebrowser.sites is a file and no urls there? What am i missing. The code gave an error from get go, cannot import fb_site.urls. Can you help?