Ok, now I'm really worried. That error message is telling you quite clearly that you're attempting to access the firstname field, from the field list table. And you can't, because there's no such field in that table

I'm worried because there are no appropriate references to such a field, table or even a variable called $firstname in your code

Oh, hang on:

my $sth = $dbh->prepare("INSERT into people (fornavn, 
efternavn, cpr, adresse, zip, city, tjenestested) 
values ($fornavn, $efternavn, $cpr, $adresse, $zip, 
$city, $tjenestested)");
[download]

will result in the SQL statement being something along the lines of: INSERT into people(fornavn...) values (tommy, ...);. Which is, of course, incorrect: those value strings need to be quoted. You see all those earlier posts with many, many question marks in them? Well, this is exactly why they were there. Try changing your statement in a similar fashion