OS X Server FTP server
I suggest you use what comes with OSX, namely sftp/scp, included with every OSX since the age of dawn. 

Enable SSH in the sharing (Remote Login), configure what users have access and then try to use sftp from the Terminal (if you are familiar with it). Try 

man sftp


to see the help. 


  DESCRIPTION
       sftp is an interactive file transfer program, similar to ftp(1), which
       performs all operations over an encrypted ssh(1) transport. 


You have the benefits of "ftp-like" plus everything is encrypted. 

If you still want to go ahead and use ftp, I suggest you take a look at ftpd conf file, located in /etc/ftpd.conf and /etc/ftpusers 

In any case, take a look at the man page for ftpd.conf and ftpusers:

man ftpd.conf
man ftpusers


…to see other options you can add there (because the default one will be most likely empty or with little things in it).

There's no pretty program to configure FTP on OSX (there is on the Server version as far as I can remember).

Please note that FTP is not a very secure protocol by default and hence it should be running inside a chroot. (hint: man ftpchroot).