Need help with Hashes

Hey, I was reading a tutorial on Perl. So far I understand everything, except hashes. I have absolutely no idea how to use them. Here's my failed attempt at a "word frequency counter". The tutorial I read doesn't explain hashes very well. So go ahead and laugh at my feeble attempts.

Code:

use feature ':5.10';

my @word = "erere"
my %letter_e = ( "e" => 1 );
say "%letter_e";