ftp <server ip>
enter login details, once in you should have a shell like interface.
binary - puts it into binary mode
ls - list files/directories
get <file> - downloads file
put <file> - uploads file
mget <files i.e *.*> - downloads many files
mput <files i.e *.*> - uploads many files
you could also get Gftp (GUI ftp client) -
http://gftp.seul.org/
if its in one of your sources:
su
apt-get install gftp