please help me, fix net2ftp problem

when i want to set folder permision, did not work.
and a message like this:

Unable to execute site command chmod 0777 / Note that the CHMOD command is only available on Unix FTP servers, not on Windows FTP servers.

please help me solve this problem, and provide step by step solving this problem.
I've read this,
but still do not understand
give me the steps that are easier to understand, to solve this problem

I use a real server, ubuntu os

Please check your folder permission.
It should belongs to vsftpd:www-data users.

Execute this command to fix the permission problem:

# chown -R vsftpd:www-data /var/www/vhosts/[yourftpuser]/

# chmod -R u+w /var/www/vhosts/[your_ftp_user]/*