For those Who already know that method
OK Readers, -
>After installing the add-on restart the browser
>Goto FreeSMSDelivery and register yourself
Sign in the freesmsdelivery
Sign in the freesmsdelivery - See more at: http://mobile-tutorials.blogspot.com/2013/06/make-sms-bomber-full-tutorial.html#sthash.5Sz9Mu2B.dpuf
Then Type the message and victim's number and click on "Send".
Click on Stop in left bar -
Select the number of messages you want to send in max tab
Then Click on "Play loop"
And see your Browser as an Bomber -