Here's a quick snippet that should suggest the type of structure that could work for the task:

my %hash;
while (my $line=<IN>) { # I assume an open IN filehandle
  chomp $line;
  ($username, $realname, $pwd) = split /\t/, $line; # I assume tab del
+imiter
  $hash{$username} = [$realname, $pwd];
}
[download]

Then you can access someuser's realname or password like:

$realname = $hash{'someuser'}->[0];
$pwd = $hash{'someuser'}->[1];
[download]

My recommendation would be to look at the references manpage for the background on how to build and work with simple data structures.

Good luck.

..Guv