how to install ftp server vsftpd and configure on centos

 yum list installed | grep ftp
 1083  yum install vsftpd
 1084  chkconfig vsftpd on
 1085  service vsftpd start

creat group
   groupadd ftp-users
   chown root:ftp-users /var/www/html/

adduser to ftp group 
  useradd -g ftp-users -d /var/www/html/ imran
create password for user.

 passwd imran

how to change password of ftp user.
  passwd imran
 enter new password;
 retype password: 

how to restrict and lock ftp user when not needed

passwd -l username{ftp user}

how to unlock the ftp user when needed

passwd +l username {ftp user}