php code after "Are you sure" is cliked

Thank you for your great plugin.

I need to write a php code if user accept to submit the form (After Are you sure). please help me where to add this code.

this code (change a field in database for the user to not allow him to send another form till admin accept this one) like a boolean field = 1,
till admin change it to 0. I know how to write it but my question is where to add it?

regards

http://wordpress.org/extend/plugins/si-contact-form/