Create multiple ftp user in centos 6 and point to /var/www/html/dir

Dear,

How to create multiple FTP user and point these users in /var/www/html/abcftp or xyzftp and login abcftp and provide these user “abcftp” password then these user access only abc directory not other and same as create next ftp (or new ftp) user like xyzftp and login xyzftp and provide these user password then these user access only xyz directory not other.

plz provide full documentations.

thanks