The DBI module works just the same for updates and inserts, you just supply the data on call to execute:

my $sth = $dbh->prepare('INSERT INTO table VALUES(?, ?, ?)');

# insert two rows with three numbers each:

$sth->execute(3, 4, 5);
$sth->execute(6, 7, 8);
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The documentation is quite good, although it contains much more than you need for your first steps. Try to skim over it nonetheless.

There's also A Short Guide To DBI which might be more suitable for the beginner, and it's quite well written.

(Update: I first wrote execute instead of prepare, thanks pKai++)