Firstly, you've posted in the wrong section of the forum. See Where should I post X?. Since you have yet to execute this code I wont delve too deeply into it, you should test and debug this, however your code lacks:

use strict;
use warnings;
[download]

See Use strict and warnings.

If you simply want to run this script, try the following from the command prompt (terminal):

Should you wish to start learning perl the following links are useful:

• http://learn.perl.org
• http://perldoc.perl.org
• The Tutorials section of this site.

Update: I've moved the node since posting.