I can see that something is wrong with your user account. You either messed up your preorder in wich case you should contact wolfire about that
[email protected] or you are just trying to fool us into a belief that you preordered Overgrowth.
OK, i believe you really preordered but something went wrong or you didn't get your preorder key so you can't accsess to the Secret preorder forum now.
First i would suggest you to give it some time and then check your e-mail (also junk mail) and then you should receive 2 e-mails from wolfire
1 should be named Thanks for preordering Overgrowth! that contains a link to your personal URL where you can find Your secret alpha key.
Hope this helps and you are not trying to fool us.