Almost there! There are a few things you should clean up in addition to figuring out how get() works.

use strict;

Lexically scope all of those variables with "my" to make strict happy.

"Hardcode" your desired local directory, and tell get() about it.

You don't need to add a newline to the cwd().

Your syntax for printing the filelist with newlines won't work. Use map instead.

Add some error checking and feedback.

#!/usr/local/bin/perl -w

use strict;

use Net::FTP;

my $hostname = 'mirror.anl.gov';
my $username = 'anonymous';
my $password = 'username@domain.com';

# Hardcode the directory and filename to get
my $home = '/pub';
my $filename = 'motd';

# Hardcode the local directory
my $localdir = '/home/boy/';

# Open the connection to the host

my $ftp = Net::FTP->new($hostname)
    or die "Cannot connect to $hostname: $@";     # Construct object

$ftp->login($username, $password)
    or die "Cannot login ", $ftp->message;;       # Log in

$ftp->cwd($home)
    or die "Cannot change working directory ", $ftp->message;# Change 
+directory

my @filelist=$ftp->ls($home);        

print map { "$_\n"} @filelist;

# Now get the file and leave
$ftp->get($filename,$localdir.$filename)
    or die "Cannot get $filename: $@"; 

$ftp->quit;
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