billing and traffic control script

Iam a new guy in mikrotik products and i have just bought an rb1000 router.its running version 3.23. iam facing problems in writing some scripts to automate my system.

  1. need a script that monitors monthly usage for an ip address and disable browsing as the limit is exceeded.
  2. send an email to client about how they have used their allocated monthly traffic.
    for the 1st option, i tried this script i found on the internet but its not running.i just copied it to my scheduler with the winbox application.i think the routeros is failing on the option :set traffic xxxxxxx because if i got to my mikrotik terminal prompt and type :set ? the option that is there is :set i .i dont know how to go about it and i need to implement this as soon as possible.

:local traffic
/queue simple
:for i from=1 to=254 do={
:set traffic [get [find target-addresses=“192.168.7.$i/32”] total-bytes]
:if ($traffic > 1000000000) do={
/ip firewall filter
add chain=forward comment=“Oh behave, baby!”
src-address=(“192.168.7.$i”) dst-address=0.0.0.0/0 action=drop
}
}