#!/usr/bin/perl
use strict;
use warnings;
use File::Find;

# the dir you're 'find'ing from
my $dir = shift || '.';

# the file you're looking for
my $file = 'blah';

# the results you want
my @results;

# the function you perform on each find value
sub looking_for_file
{
    # push full filename to an array if file and name is $file
    push(@results, $File::Find::name) if(-f $_ && $_ eq $file);
};

# the result you want, using File::Find::find()
#   (not the external 'find' program)
find \&looking_for_file, $dir;

# print your results
print("my results are: @results\n");

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
use File::Find;

# the shorter version
my @results;
find sub{-f $_ && $_ eq 'blah' && 
    push(@results,$File::Find::name)}, shift || '.';
print("my results are: @results\n");