This should fit your requirements. You need to modify the $word variable.

Remember, when you need to count occurances, the hash is your friend.

use strict;

my $word = 'abcdefabcdeab';
my ( %counters, $total );
while ( $word =~ /([a-c])/gi )
{
    $counters{$1}++;
}

foreach my $letter ( sort keys %counters )
{
    print "\n$letter: " . $counters{$letter};
    $total += $counters{$letter};
}
print "\nTotal: $total";
[download]

Produces:

a: 3
b: 3
c: 2
Total: 8
[download]

I hope this helps.