You have to take a look at stat, opendir, open and File::Find::Rule. By using those mentioned functions and module, you can achieve your target. As planetscape++ said, you have to try to write the code and post the code if you have any problem. Below is a sample code.
use strict;
use warnings;
use File::Find::Rule;
my ($filename, $giventime, $directoryname);
my @files = File::Find::Rule->file()
->name( "$filename" )
->ctime ("< $giventime")
->in( "$directoryname" );
for my $file (@files)
{
open ($fh, '<', $file) or die ("$!");
}
update: Added code