Well, you havent told me what the problem is, but I'll try to help with what I can.

sub add_customer{
  my ($company,$fname,$lname,$phn,$b2stre,$b2city,$b2stat,$b2zip,$s2st
+re,$s2city,$s2stat,$s2zip) = @_;
  my ($handl) = DBI->connect('DBI:mysql:advanc'); or die "Couldn't con
+nect to database: " . DBI->errstr;
  my $sql  = "INSERT INTO customers 
  (Company,FirstName,LastName,PhoneNumber,Bill2Street,Bill2City,Bill2S
+tate,Bill2Zip,Ship2Street,Ship2City,Ship2State,Ship2Zip) 
  VALUES (?,?,?,?,?,?,?,?,?,?,?,?) ";
  my $sth = $handl->prepare($sql) or die "Couldn't prep statement";
  $sth->execute($company,$fname,$lname,$phn,$b2stre,$b2city,$b2stat,$b
+2zip,$s2stre,$s2city,$s2stat,$s2zip) or die "Couldn't add customer";
}
[download]

changes

• named the insert field names. Dont know if this matters to mysql, but Informix is picky that way
• added "or die" to $sth to catch those before the execute()
• shortened the varnames. not a nit, im just a lazy typist