Where do I put the $args

You don't. In some of the Net modules, you can use a %args for options, but since this is LWP, there's a slightly different way to do that. For example, in the example that I gave you, I tried to keep it simple, step-by-step. Lets look at another way to do it.

$req = HTTP::Request->new(POST => $self->{'baseurl'}, $args);

First, you're missing a shebang line( #!/usr/bin/perl ) and strictures. You also need to declare your variables with my. Another problem is your use of $self->{'baseurl'}---What's that? You didn't declare $self nor $args. Putting it altogether:

#!/usr/bin/perl

use strict;
use warnings;
use LWP::UserAgent;

#using http://www.example.com for our $url
my $req = HTTP::Request->new(POST => 'http://www.example.com');
[download]

Note that the url should be absolute; also, I dropped $self->{'baseurl'} and $args because they weren't necessary and didn't do anything. Now you know where to put $args:).