Well first of all, its not very smart to post that you are cracking into a server here, especially seeing as how your IP is logged by the BBS.
Also, trying to use a Brute Force cracking utility on a privite FTP server Usually isn't a good idea. Most people who setup these servers and leave them running. Make it so it bans & logs your IP address after so many authencation errors. A lot of times this is set to three.
Now about configuring brutus, I would suggest going to http://www.google.com
and searching for 'Brutus Cracking utility' that should give you all the info you want and more. Also there are proably help pages associated with that program that were installed along with it. My suggestion would be to read those.