script for memory monitoring and sending mail to users in network

Linux and Unix-Like Ubuntu
1

I m working on a script which monitors the disk usage and send a mail to the users if it reaches a limit of 90%.
hlp me

2

Where did you get stuck - show the problem.

3 
df -k | awk 'int($5) > 95{ 
  subject = $1 " More than 95% disk usage "
  email = "navdeep5673@hotmail.com"
  cmd = "mailx -s \"" subject "\" " email
  cmd  | getline #or system(cmd)
  }
'

Now what to do?

Please help me. I'm not professional.