The error message tells you what's wrong, the SimHMAC.pm file cannot be found in any of the places that perl searches. I assume you've got it installed in the same place as your script, add

use lib '/home/tznius/www/cgi-bin/store/library/';
[download]

at the beginning of your scripts (or modify the path accordingly if you've got the library installed somewhere else).

P.S. You should use <code></code> tags around any code or shell output.