Gen Key command done correctly

[Ladislav Hagara]

>> You must run "gpg --edit-key" and then ...
>>     
>
> Next question ...
>
> Sub-key generated.
>
> Do I still encrypt to the original public key?

Nobody can encrypts files for you if your public key doesn't contain
encrypt subkey.

>  And thus, is the sub-key
> used automatically? .. I ask because it's not intuitively obvious to me
> how I tell gpg to select that sub-key since Thunderbird already uses the
> key generated originally to the email address.

The subkey will be used automatically. You just have to export your
public key again and your partners have to import it (only this subkey
will be really imported).
Without encrypting subkey the Thunderbird (Enigmail) will abe able only
check your signature but nobody will be able to encrypt email for you.

-- 
Ladislav Hagara