...

my $userAgent = LWP::UserAgent->new();
my $request = POST 'http://example.com', Content_Type => 'multipart/form-data', Content => [file_0 => ['options2.txt']];

$request->authorization_basic('username', 'password');
my $response = $userAgent->request($request);
print $response->error_as_HTML . "\n" if $response->is_error;