function checkform(form) {

  if (form.first_name.value == "") {
    alert( "Please enter your first name." );
    form.first_name.focus();
    return false ;
  }
  
  if (form.phone.value == "") {
    alert( "Please enter your phone number." );
    form.phone.focus();
    return false ;
  }
  
   if (form.email.value == "") {
    alert( "Please enter your email address." );
    form.email.focus();
    return false ;
  }
  
  if (form.comment.value == "") {
    alert( "Please enter your comments or feedback." );
    form.comment.focus();
    return false ;
  }
  
  if (form.security_code.value == "") {
    alert( "Please enter the security code." );
    form.security_code.focus();
    return false ;
  }

return true ;
}