#sample set up a hash of hashes
my %h =
(
    key1 => { subkey11 => subval11, subkey21 => subval21 },
    key2 => { subkey12 => subval12, subkey22 => subval22 },
);

#access it
print $h{key1}->{subkey11};

#loop it
for ( keys %{$hash->{key2}} )
{
    print $hash->{key2}->{$_};
}