function checkform ( form )
{

  
  if (form.first_name.value == "") {
    alert( "Please enter your first name." );
    form.first_name.focus();
    return false ;
  }
  
  
   if (form.last_name.value == "") {
    alert( "Please enter your last name." );
    form.last_name.focus();
    return false ;
  }
  
  
    if (form.organization.value == "") {
    alert( "Please enter the name of your organization." );
    form.organization.focus();
    return false ;
  }
  
    if (form.address.value == "") {
    alert( "Please enter your address." );
    form.last_name.focus();
    return false ;
  }
  
  
   if (form.email.value == "") {
    alert( "Please enter your email address." );
    form.email.focus();
    return false ;
  }
  
  return true ;
}