Perhaps a word of explanation is advised here, so you know where you went wrong (since you were oh so close to the solution).

The structure you have made with the %drw-hash is as follows:

$VAR1 = {
          'dave' => {
                      'three' => 'dthree',
                      'one' => 'done',
                      'two' => 'dtwo'
                    },
          'eileen' => {
                        'three' => 'ethree',
                        'one' => 'eone',
                        'two' => 'etwo'
                      }
        };
[download]

(Data::Dumper is a very useful module to show you the structure of your arrays, hashes and objects -- do have a look at it)

As you see, the keys "dave" and "eileen" point to another hash-structure, it means they are references to another hash.

Now to access a variable (scalar, array, hash) through a reference you have to dereference the reference, which results in turning the reference back into the variable it pointed to.

Dereferencing is easy: just put the magic $, @ or % in front of the reference and the reference turns into the variable of the kind indicated by the prefix (of course you cannot turn a reference for a scalar into a hash, ...; you have to respect the type of the reference!)

That is why you cannot say %drw{eileen} (Which is wrong in any case, at least it should be $drw{eileen}) and expect it to give you access to the keys and values of the second level hash (Try it and you will see you get an answer like HASH(0x1c2522c), indicating you were dealing with a reference to a hash), but have to dereference it so you can get to the second level of the Hash-of-Hashes: %{$drw{eileen}}