To use BrowCoFtp you must have rights to login on web server on port 21 with username and password.
BrowCoFTP use the functions 'ftp_connect' and 'ftp_login' on port 21. On to some web servers you don't have rights to use this port for ftp connexion.
If you don't know witch is your username and password for your ftp account, please ask your hosting administrator.
Some accounts use username like your_name@your_webserver.com with some password.

Solution for you is to ask web server administrator.