To import your Facebook contacts to Google +, need to have your contacts file in CSV format. But unfortunately there is no feature in FB to export contacts so you need to use this method to get all your contacts from Facebook to Google+.
1. Login to your Yahoo mail account (if you dont have create one)
2. Goto contacts and Import
3. Choose facebook and go to contacts again
4. From actions button on navigation bar choose export all
5. Choose Yahoo! csv format, then Save file
6. Login to Gmail account
7. Goto contacts and Import contacts
8. Browse to Yahoo CSV file
9. Goto your Google+ circles page and now you can see all your facebook friend, now you can add them to appropriate circles.