Assuming you do not have anon logins your config needs lines:
anonymous_enable=NO
local_enable=YES
userlist_deny=NO
userlist_enable=YES
chroot_local_user=YES
write_enable=YES
You need to put a list of users in /etc/vsftpd.user_list with one user per line.
Restart your services after editing
Here's a good link for creating no-shell accounts which is a good idea for ftp only users.
http://www.tldp.org/LDP/solrhe/Secu...ap29sec295.html